Additive manufacturing of active devices using dielectric, conductive and magnetic materials

ABSTRACT

The present disclosure relates to a process, system and apparatus for multi-material additive manufacturing process comprising: extruding an extrudable material through a nozzle capable of moving along one or more axis and concurrently extruding one or more filaments, wherein the filament is embedded in, on or about the extrudable material from the nozzle.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority of U.S. Application Ser.No. 62/371,581 (filed on Aug. 5, 2016), which is incorporated byreference herein in its entirety.

STATEMENT OF FEDERALLY FUNDED RESEARCH

This invention was made with govern support under NSF award #1317961:“NRI: Small: Additive Manufacturing of Soft Robot Components withEmbedded Actuation and Sensing” awarded by National Science Foundation.The government has certain rights in the invention.

TECHNICAL FIELD

The present disclosure relates generally to the fields of additivemanufacturing/3-D printing, robotics, electronic packaging, biomedicaldevices, and other fields.

BACKGROUND

Without limiting the scope of the disclosure, its background isdescribed in connection with 3-D printing/additive manufacturing.

Multi-material and composite additive manufacturing (AM): Objet's(Rehovot, Israel, now merged with Stratasys) Polyjet™ technology canprint structures from two dielectric photopolymers. Multi-materialstereolithography using multiple vats of liquid (dielectric)photopolymer has been demonstrated [Wicker et al., 2009], andmulti-material FDM has been explored [Espalin, 2012]. Ceramic and metalcomposites made with FDM have been described by several researchers[Kumar and Kruth, 2010; Vaidyanathan et al., 1999; Onagoruwa et al.,2001; McNulty et al., 1998; Agarwala et al., 1996] and FDM-producedinjection molding dies using metallic composites were made [Masood andSong, 2004] and characterized for thermal conductivity [Nikzad et al.,2011].

Electromechanical structures by AM: FDM of ABS and low-melting pointalloys such as Bi58Sn42 has been used to make simple multilayerstructures having a dielectric structural component and an electricalconductor [Mireles et al., 2012]. However, this approach is limited bythe relatively high electrical resistance of solders (Bi58Sn42 solderhas ˜22 times higher resistivity than annealed Cu); maintaining theintegrity of solder melting at 138° C. while adjacent to polymerdeposited at a higher temperature; the inability to use solder to makemagnetic elements for electromagnetic actuators; mechanical weakness;brittleness common in Bi-based solders; significant electromigrationrisk; mutual adhesion of molten solder to polymer; and throughput(polymer and metal dispensed from separate nozzles). Others havedemonstrated simple electromechanical/electronic devices fabricated byAM including relays, timing circuits using integrated circuits addedmanually, and flashlights [Periard et al., 2007; Malone and Lipson,2007; Alonso et al., 2009; Malone and Lipson, 2008]. For example, asolenoid was fabricated using solder for coils, silicone for dielectric,and iron powder in grease for a core [Alonso et al., 2009]. While usefulas a demonstration, the process was cumbersome and not fully-automated.Stratasys (Eden Prairie, Minn.) and Optomec (Albuquerque, N. Mex.) havedemonstrated fabricating structures in rigid polymer using FDM anddepositing traces of silver nanoparticle ink using aerosol jetting onthe exterior surfaces of the structure [O'Reilly and Leal, 2010]. Traceresistivity can be as low as 1×10-5 ohm-cm, but part surface roughness,applicability to accessible surfaces only, and the need to sinter theink remain challenges. Similar work has been done by researchers usingstereolithography and micro-dispensing pumps [Lopes et al., 2012]. Inboth these efforts, traces are necessarily confined to external surfacesunless channels are manually filled by pumping [DeNava et al., 2008];therefore the circuitry, like that produced by O'Reilly and Leal, is nottruly 3-D and solenoid-type coils seem impossible. Moreover, theseprocesses are not integrated or fully-automated. Others have postulatedthe use of curved layers to produce integrated electromechanicalstructures using FDM, insisting incorrectly that circuits cannot beproduced using planar processes due to inter-layer connectivity issues[Diegel et al., 2011]. Curved layers introduce many difficulties and inany case do not truly obviate the need for a solution to interlayerconnectivity.

More recently, Voxel8 Inc. (Somerville, Mass.) has developed amulti-material 3-D printer using FDM to deposit a thermoplastic polymeras dielectric and structural element, and an extrusion head to depositbetween the layers of thermoplastic a rapidly-setting silver-basedconductive ink to form interconnects. However, the Voxel8 processrequires a separate step to deposit the conductor, and the ink isapproximately 30 times higher in resistivity than metallic copper, hasunknown maximum current density, and is extremely costly (indeed, over1500 times as costly as copper wire for a “wire” of the same totalresistance).

Wire embedding AM: While most prior efforts to integrate conductive anddielectric materials in AM assume that the conductive material cannot bea solid metal, a student project called “SpoolHead” investigated the useof FDM and metal wire to make 3-D circuits [Bayless et al., 2010],inspired by an adhesive-coated wire-based AM method [Lipsker, 2000].Earlier work [e.g., Rabinovich, 1996] explored generating 3-D structuresusing laser welding of flat-sided wire. The SpoolHead project aimed todeposit thermoplastic using FDM, then interrupt the process and lay downwire while attempting to secure it to the polymer by remelting. Later, aprocess developed at the University of Texas at El Paso began to developan approach [Aguilera et al., 2013] similar to SpoolHead, but in whichwire is pushed just below the surface of a printed layer using eitherultrasonic vibration or Joule heating to reflow the thermoplastic matrixmaterial, allowing wire embedding. Junctions between wires or betweenwires and added components are created by laser welding. Due to thecomplex and costly equipment required and the relatively low processingspeed, the process is not economical for producing mostelectromechanical or electronic devices, especially in significantvolume. Moreover, the embedding process requires that the matrix bereflowable.

Elastomer AM: Additive manufacturing with elastomer materials iscurrently available. Polyjet can print with elastomeric photopolymer,and 3D Systems' (Rock Hill, S.C.) selective laser sintering process canwork with powdered elastomer. Both techniques produce rather fragileparts, and neither is capable of selectively incorporating conductivematerials. Elastomers have been cast and combined with other materialsusing a subtractive/additive process [Cutkosky and Kim, 2009]. Of mostrelevance, FDM of thermoplastic elastomers was demonstrated at VirginiaTech [Elkins et al., 1997] by changing the design of a standard FDMprinthead to reduce the risk of filament buckling and to optimizefilament feed rollers. Also, Stratasys commercialized for some time anelastomer FDM material branded as E20.

Molded Interconnect Device: Molded interconnect device (MID) is a deviceproduced via injection molding of thermoplastic and having circuitryintegrated into the device. The process is limited to locating circuitelements on the surface of the device; they cannot be locatedinternally, so it would, for example, be impossible to produce amulti-layer, 3-D coil. Moreover, MID conductors tend to be thin and notcapable of carrying higher currents.

SUMMARY

The present disclosure relates to a multi-material additivemanufacturing process comprising: extruding an extrudable materialthrough a nozzle capable of moving along one or more axis andconcurrently dispensing one or more filaments, wherein the filament isencapsulated within or on an extrudate extruded from the nozzle. In oneaspect, the filament is dispensed so as to become encapsulated nominallycoaxial with the extrudable material. In another aspect, the filament isa metal, a semiconductor, a ceramic, a synthetic or natural thread, aconductor, a conductive polymer, a magnetic material, a conductivepowder, a fiber, an optical fiber, a tube, a coaxial cable, or aconductive thermoplastic polymer. In another aspect, one or morefilaments are wound into coils, formed into a block, formed into acylinder or other shapes to form one or more actuators, sensors, thermalmanagement structures (e.g., made using wire and/or a compositecontaining metal or boron nitride particles), switches, transformers,fuses, resistors, capacitors, supercapacitors, inductors, chokes,antennae (e.g., patch, fractal), batteries, external connecting pads,variable-resistance resistors, force sensors, pressure sensors,temperature sensors, cores and armatures for electromagnetic devices,capacitor plates, heat sinks, solenoids, heat conduction structures orpower supplies. In another aspect, two or more filaments are formed intoone or more mechatronic structures. In another aspect, the extrudablematerial is a thermoplastic material, a dielectric material, anelastomeric material, a thermoset material, a moisture-curing material,an air-hardening material, or a deformable material. In another aspect,the one or more filaments are connected electrically by a metal, asemiconductor, a ceramic, a conductor, a conductive polymer, aconductive powder, or a conductive thermoplastic polymer. In anotheraspect, the process further comprises the step of connecting one or moreintegrated circuits, actuators, sensors, thermal management structures,switches, transformers, fuses, resistors, capacitors, inductors,antennae, batteries, external connecting pads or power supplies to theone or more filaments. In another aspect, the one or more filaments aredefined further as one or more sacrificial filaments that when removedcreate one or more open conduits or vias. In another aspect, wherein theone or more filaments are surrounded by a dielectric and the dielectricis removable by at least one method selected from laser processing,heating, mechanical stripping, or plasma etching. In another aspect, theone or more filaments are joined by welding, soldering, brazing,ultrasonic or thermosonic bonding, crimping, winding, pressure contact,or mutual entanglement. In another aspect, the process further comprisesthe step of segmenting (e.g., cutting or breaking) the one or morefilaments upon deposition. In another aspect, the process furthercomprises a control system (e.g., a computer) that controls the steps ofextruding the thermoplastic material and the one or more filaments.

Another embodiment of the present disclosure relates to a system for amulti-material additive manufacturing process comprising: a first nozzlefor extruding an extrudable material through a nozzle capable of movingalong one or more axis; and a filament, fiber, or wire dispenser thatconcurrently extrudes one or more filaments, wherein the filament isencapsulated within or on extrudate from the nozzle. In one aspect, thefilament is extruded nominally coaxial with the thermoplastic material.In another aspect, the filament is a metal, a semiconductor, a ceramic,a conductor, a conductive polymer, a magnetic material, a conductivepowder, a fiber, an optical fiber, a tube (e.g., through which fluid canflow, or shape memory wires may be routed), a coaxial cable, or aconductive thermoplastic polymer. In another aspect, the one or morefilaments are wound into coils, formed into a block, formed into acylinder or other shapes to form one or more actuators, sensors, thermalmanagement structures, switches, transformers, fuses, resistors,capacitors, inductors, antennae, batteries, external connecting pads,variable-resistance resistors, force sensors, pressure sensors,temperature sensors, cores and armatures for electromagnetic devices,capacitor plates, heat sinks, solenoids, heat conduction structures orpower supplies. In another aspect, the two or more filaments are formedinto one or more mechatronic structures. In another aspect, theextrudable material is a thermoplastic material, a dielectric material,an elastomeric material, or a deformable material. In another aspect,the one or more filaments are connected electrically by a metal, asemiconductor, a ceramic, a conductor, a conductive polymer, aconductive powder, or a conductive thermoplastic polymer. In anotheraspect, one or more integrated circuits, actuators, sensors, thermalmanagement structures, switches, transformers, fuses, resistors,capacitors, inductors, antennae, batteries, external connecting pads orpower supplies, to the one or more filaments. In another aspect, the oneor more filaments are defined further as one or more sacrificialfilaments that when removed create one or more open conduits or vias. Inanother aspect, wherein the one or more filaments are surrounded by adielectric and the dielectric is removable by at least one methodselected from laser processing, heating, mechanical stripping, or plasmaetching. In another aspect, the one or more filaments are joined bywelding, soldering, brazing, ultrasonic or thermosonic bonding,crimping, winding, pressure contact, or mutual entanglement. In anotheraspect, the system further comprises a cutter capable of cutting the oneor more filaments upon deposition. In another aspect, the system furthercomprises a computer that controls the steps of extruding thethermoplastic material and the one or more filaments.

Yet another embodiment of the disclosure relates to an apparatus for amulti-material additive manufacturing process comprising: a first nozzlefor extruding a thermoplastic material through a nozzle capable ofmoving along one or more axis; and a filament dispenser thatconcurrently extrudes one or more filaments, wherein the filament isencapsulated within or on extrudate from the nozzle. In one aspect, thefilament is extruded nominally coaxial with the thermoplastic material.In another aspect, the filament is a metal, a semiconductor, a ceramic,a conductor, a conductive polymer, a magnetic material, a conductivepowder, a fiber, an optical fiber, a tube, a coaxial cable, or aconductive thermoplastic polymer. In another aspect, the one or morefilaments are wound into coils, formed into a block, formed into acylinder or other shapes to form one or more actuators, sensors, thermalmanagement structures, switches, transformers, fuses, resistors,capacitors, inductors, antennae, batteries, external connecting pads,variable-resistance resistors, force sensors, pressure sensors,temperature sensors, cores and armatures for electromagnetic devices,capacitor plates, heat sinks, solenoids, heat conduction structures orpower supplies. In another aspect, the two or more filaments are formedinto one or more mechatronic structures. In another aspect, theextrudable material is a thermoplastic material, a dielectric material,an elastomeric material, or a deformable material. In another aspect,the one or more filaments are connected electrically by a metal, asemiconductor, a ceramic, a conductor, a conductive polymer, aconductive powder, or a conductive thermoplastic polymer. In anotheraspect, one or more integrated circuits, actuators, sensors, thermalmanagement structures, switches, transformers, fuses, resistors,capacitors, inductors, antennae, batteries, external connecting pads orpower supplies, to the one or more filaments. In another aspect, the oneor more filaments are defined further as one or more sacrificialfilaments that when removed create one or more open conduits or vias. Inanother aspect, wherein the one or more filaments are surrounded by adielectric and the dielectric is removable by at least one methodselected from laser processing, heating, mechanical stripping, or plasmaetching. In another aspect, the one or more filaments are joined bywelding, soldering, brazing, ultrasonic or thermosonic bonding,crimping, winding, pressure contact, or mutual entanglement. In anotheraspect, the apparatus further comprises a cutter capable of cutting theone or more filaments upon deposition. In another aspect, the apparatusfurther comprises a computer that controls the steps of extruding thethermoplastic material and the one or more filaments.

Thus, the Fiber Encapsulation Additive Manufacturing (hereinafter“FEAM”, formerly known as 3-D Polymer+Wire Printing, or “3dPWP”))process, system, and apparatus of the present disclosure provides atruly multi-material Additive Manufacturing (AM) process that canfabricate functional electromechanical devices using a polymer and awire. More generally, the polymer may be another, non-polymeric materialsuch as a ceramic, and the wire may be a fiber or filament of anycomposition, a tube, a solidifying liquid, or other element. The term“polymer” should be understood to include all materials extrudable froma nozzle and solidifiable by cooling, evaporation, thermal curing, UVcuring, etc. The term “wire” should be understood to include wire (e.g.,metal wire) and any fiber or filament such as carbon fiber, glass fiber,polymer fiber, small-diameter tubing, and all other materials andstructures having a substantially filament or fiber-like shape. Thesematerials can be monofilament or have multiple strands, sometimesimpregnated and held together by a resin similar to prepreg used incomposite manufacturing. FEAM greatly extends AM to enable automatedfabrication of multi-material, multi-functional components and deviceshaving embedded 3-D circuitry, actuators, sensors (e.g. accelerometers,strain gauges, tactile arrays, and touch screen overlays), thermalmanagement structures (e.g., heat sinks, heat pipes, fluid channels,cooling fluid pumps), switches, transformers, fuses, resistors,capacitors, inductors, and antennae, among other elements.

The key aspect of the FEAM process is simultaneous co-deposition of afiber and an extrudable material that surrounds and encapsulates thefiber. This aspect alone makes possible a variety of objects to befabricated. However, important additional aspects of the FEAM process,which provide more capability, are the ability to stop and start thefiber (achieved for example using a feeder/cutter as described below),and the ability to join fibers together to form junctions which allowelectric currents (or in some embodiments optical signals) to flow fromone fiber to another, link fibers mechanically so that stresses can becoupled from one fiber to another, etc. The potential impact of FEAM isin providing a new means of monolithically producing fully-customizedfunctional components and systems without the need for assembly,directly from digital data. In the semiconductor industry, monolithicfabrication has made possible the integrated circuit. At the macroscale—and incorporating mechanical, not just electricalelements—monolithic fabrication can also have a huge benefit, reducingcost while increasing reliability and quality, and enabling productsimpossible with traditional approaches.

The methods and apparatus of FEAM incorporate materials such as metalwire (e.g., nickel, copper, aluminum, silver, gold, superelasticnickel-titanium, and solder: either pure or plated with such metals asgold and silver for corrosion resistance and/or polymer compatibility)and conductive composites into a structure or device that is built upone layer at a time in an additive manufacturing process. Morespecifically, FEAM provides for simultaneous deposition of conductiveand/or ferromagnetic wires together with polymer: either a pure polymer(e.g., an elastomer) or an electrically conductive polymer composite(ECPC) composed of polymer and conductive filler particles. The abilityto controllably deposit these three materials (and in some cases,others) provides enormous flexibility in creating mechatronic structureswith embedded electromagnetic elements.

The present disclosure provides a multi-material additive manufacturingprocess, system, and apparatus for fabricating 3-D structures, devices,components, systems, products, and assemblies comprising polymer andwire, and in some embodiment variations, also conductive polymercomposite. Such fabricated objects, or articles, are generally active,in the sense of incorporating circuitry, actuators, and/or sensors, andcan be used in robotics, defense systems, medical devices, consumerelectronics, and many other fields.

The present disclosure provides a process, system, and apparatus forfabricating a 3-D structure, device, component, system, product, orassembly using a layer-by-layer, additive manufacturing process whereinan extrudate that forms at least a portion of a layer comprises a matrix(i.e., structural, build, or model) material and a wire, fiber, or fluidconduit (hereinafter “fiber”) encapsulated at least in part within thematrix material. In some implementations, a major (i.e., longitudinal)axis of the fiber can be substantially parallel to that of theextrudate, while in others, the fiber can be in any orientation relativeto the extrudate. For example, the fiber can be coiled or arrangeddifferently within the extrudate.

The present disclosure provides a process, system, and apparatus forfabricating a 3-D structure, device, component, system, product, orassembly using a layer-by-layer, additive manufacturing process whereinan extrudate that forms at least a portion of a layer comprises adielectric matrix material and an encapsulated metallic wire whose majoraxis is substantially parallel to that of the extrudate.

The present disclosure provides a process, system, and apparatus forfabricating a 3-D structure, device, component, system, product, orassembly using a layer-by-layer, additive manufacturing process whereina matrix material and a fiber are co-deposited, resulting in a fiberencapsulated within a matrix.

The present disclosure provides a process, system, and apparatus forfabricating a 3-D structure, device, component, system, product, orassembly using a layer-by-layer, additive manufacturing process whereina fiber encapsulated within a matrix and forming at least a portion of alayer is in some embodiment variations joined electrically,mechanically, or both to other fibers in the same or a different layer.

The present disclosure provides a process, system, and apparatus forfabricating a 3-D structure, device, component, system, product, orassembly using a layer-by-layer, additive manufacturing process whereinin some embodiment variations a metallic wire, encapsulated within aconductive matrix and forming at least a portion of a layer, iselectrically connected to other metallic wires in the same or adifferent layer through the conductive matrix.

The present disclosure provides a process, system, and apparatus forfabricating a 3-D structure, device, component, system, product, orassembly using a layer-by-layer, additive manufacturing process whereinin some embodiment variations a metallic wire encapsulated within aconductive matrix and forming at least a portion of a layer iselectrically connected to other metallic wires in the same or adifferent layer through the conductive matrix and the conductive matrixcomprises a polymer and conductive particles.

The present disclosure provides a process, system, and apparatus forfabricating a 3-D structure, device, component, system, product, orassembly using a layer-by-layer, additive manufacturing process whereinin some embodiment variations a conductive matrix comprising a polymerincludes conductive particles at a concentration above the percolationthreshold such that some contamination by dielectric material will notsignificantly lower conductance, and wherein some contamination ofdielectric material by conductive particles will not render thedielectric material conductive.

The present disclosure provides a process, system, and apparatus forfabricating a 3-D structure, device, component, system, product, orassembly using a layer-by-layer, additive manufacturing process whereinin some embodiment variations metallic wires are joined by welding,soldering, brazing, ultrasonic or thermosonic bonding, crimping,winding, pressure contact, or mutual entanglement.

The present disclosure provides a process, system, and apparatus forfabricating a 3-D structure, device, component, system, product, orassembly using a layer-by-layer, additive manufacturing process whereinin some embodiment variations a fiber surrounded by an initially fluidmatrix material is co-deposited with the matrix material to form atleast a portion of a layer and wherein the fiber is directed duringdeposition such that its major axis is substantially parallel to that ofthe extrudate by the time the matrix material has solidified.

The present disclosure provides a process, system, and apparatus forfabricating a 3-D structure, device, component, system, product, orassembly using a layer-by-layer, additive manufacturing processincluding an encapsulated filament wherein in some embodiment variationsactuators, sensors, and/or wiring are monolithically fabricated.

The present disclosure provides a process, system, and apparatus forfabricating a 3-D structure, device, component, system, product, orassembly having such elements as embedded 3-D circuitry, actuators,sensors, thermal management structures, switches, transformers, fuses,resistors, capacitors, inductors, and antennae using a multi-material,multi-functional layer-by-layer, additive manufacturing process.

The present disclosure provides a process, system, and apparatus forfabricating a 3-D structure, device, component, system, product, orassembly using a layer-by-layer, additive manufacturing process whereinin some embodiment variations an encapsulated metallic wire ismechanically soft and in some embodiment variations annealed.

The present disclosure provides a process, system, and apparatus forfabricating a 3-D structure, device, component, system, product, orassembly using a layer-by-layer, additive manufacturing process whereinan encapsulated metallic wire is in some embodiment variations circularin cross section.

The present disclosure provides a process, system, and apparatus forfabricating a 3-D structure, device, component, system, product, orassembly using a layer-by-layer, additive manufacturing process whereinan encapsulated metallic wire is in some embodiment variationsrectangular or square in cross section.

The present disclosure provides a process, system, and apparatus forfabricating a 3-D structure, device, component, system, product, orassembly using a layer-by-layer, additive manufacturing process whereinin some embodiment variations a matrix and a fiber are co-depositedalong a curved path and a spool or other fiber storage means is rotatedto counteract torsion resulting from such deposition.

The present disclosure provides a process, system, and apparatus forfabricating a 3-D structure, device, component, system, product, orassembly using a layer-by-layer, additive manufacturing process whereinin some embodiment variations a matrix and a fiber are co-depositedalong a curved path and the direction of the deposition is alternatedbetween clockwise and counterclockwise to counteract torsion resultingfrom such deposition.

The present disclosure provides a process, system, and apparatus forfabricating a 3-D structure, device, component, system, product, orassembly using a layer-by-layer, additive manufacturing process whereinin some embodiment variations a deposition head comprises at least oneflow channel for matrix material and at least one capillary for filamentdispensing.

The present disclosure provides a process, system, and apparatus forfabricating a 3-D structure, device, component, system, product, orassembly using a layer-by-layer, additive manufacturing process whereinin some embodiment variations a deposition head comprises at least oneflow channel for dielectric material and at least one flow channel forconductive material.

The present disclosure provides a process, system, and apparatus forfabricating a 3-D structure, device, component, system, product, orassembly using a layer-by-layer, additive manufacturing process whereinin some embodiment variations a deposition head comprises a flow channelfor fluid and a capillary with suitable geometry to substantiallydisplace and purge fluid from the flow channel when maneuvered withinthe flow channel.

The present disclosure provides a process, system, and apparatus forfabricating a 3-D structure, device, component, system, product, orassembly using a layer-by-layer, additive manufacturing process whereinin some embodiment variations a deposition head comprises a clamp tosecurely hold filament and wherein the clamp is fixed to a capillary andactuated by translating the capillary.

The present disclosure provides a process, system, and apparatus forfabricating a 3-D structure, device, component, system, product, orassembly using a layer-by-layer, additive manufacturing process whereinin some embodiment variations a deposition head comprises a cutter tocut filament and wherein the cutter is fixed to a capillary and actuatedby translating the capillary.

The present disclosure provides a process, system, and apparatus forfabricating a 3-D structure, device, component, system, product, orassembly using a layer-by-layer, additive manufacturing process whereinin some embodiment variations filament is dispensed or fed from adeposition head by vibration.

The present disclosure provides a process, system, and apparatus forfabricating a 3-D structure, device, component, system, product, orassembly using a layer-by-layer, additive manufacturing process whereinin some embodiment variations filament is dispensed or fed from adeposition head by anchoring the wire in substantially solidified matrixmaterial and pulling it through the deposition head.

The present disclosure provides a process, system, and apparatus forfabricating a 3-D structure, device, component, system, product, orassembly using a layer-by-layer, additive manufacturing process whereinin some embodiment variations filament is dispensed or fed from adeposition head by two or more rollers which contact the filament andadvance it through a capillary slightly larger in inside diameter thanthe filament outside diameter.

The present disclosure provides a process, system, and apparatus forfabricating a 3-D structure, device, component, system, product, orassembly using a layer-by-layer, additive manufacturing process whereinin some embodiment variations filament is cut or terminated by thesudden application of tension, twisting, or cyclic motion inducingmechanical fatigue.

The present disclosure provides a process, system, and apparatus forfabricating a 3-D structure, device, component, system, product, orassembly using a layer-by-layer, additive manufacturing process whereinin some embodiment variations filament passes through a capillary orother sheath and matrix material is removed from the region of thefilament exiting the capillary to prevent the filament from being coatedwith matrix material.

The present disclosure provides a process, system, and apparatus forfabricating a 3-D structure, device, component, system, product, orassembly using a layer-by-layer, additive manufacturing process whereinin some embodiment variations matrix material coating a filament isremoved by methods including laser processing, heating, mechanicalstripping, and plasma etching.

The present disclosure provides a process, system, and apparatus forfabricating a 3-D structure, device, component, system, product, orassembly using a layer-by-layer, additive manufacturing process whereinin some embodiment variations filament position within the extrudatealong the deposition (e.g., vertical) axis is controlled by adjustingcapillary height and/or filament feed rate and in some embodimentvariations filament position is controlled in a closed-loop fashionbased on sensing the filament position within the extrudate.

It is the object of some aspects of the disclosure to provide a process,system, and apparatus for fabricating a 3-D structure, device,component, system, product, or assembly using a layer-by-layer, additivemanufacturing process wherein in some embodiment variations filamentposition within curved extrudate in the layer plane (e.g., horizontal)is controlled by adjusting capillary rotation angle and/or printheadspeed.

The present disclosure provides a process, system, and apparatus forfabricating a 3-D structure, device, component, system, product, orassembly using a layer-by-layer, additive manufacturing process whereinin some embodiment variations toolpaths for the deposition head aredetermined such that paths which include encapsulated filament arepreferentially routed and those which do not include filament are routedat a lower priority.

The present disclosure provides a process, system, and apparatus forfabricating a 3-D structure, device, component, system, product, orassembly using a layer-by-layer, additive manufacturing process whereinseparately-manufactured components are incorporated during fabricationprocess using pick-and-place or other means.

The present disclosure provides a process, system, and apparatus forfabricating a 3-D structure, device, component, system, product, orassembly using a layer-by-layer, additive manufacturing process whereina removable and preferably soluble support material is provided and atleast some of the support material is substantially encapsulated inmatrix material to allow retention of at least some of the supportmaterial in the final structure, device, component, system, product, orassembly.

The present disclosure provides a process, system, and apparatus forfabricating a 3-D structure, device, component, system, product, orassembly using a layer-by-layer, additive manufacturing process whereina conductive matrix comprising a polymer and conductive particles isused in the formation of integrated elements such as variable-resistanceresistors, force sensors, pressure sensors, temperature sensors, coresand armatures for electromagnetic devices, capacitor plates, heat sinks,and other heat conduction structures.

The present disclosure provides a process, system, and apparatus forfabricating a 3-D structure, device, component, system, product, orassembly using a layer-by-layer, additive manufacturing process whereinthe structure, device, component, system, product, or assembly comprisesvoids, which are fluid-filled and in some embodiment variationsinterconnected.

The present disclosure provides a process, system, and apparatus forfabricating a 3-D structure, device, component, system, product, orassembly using a layer-by-layer, additive manufacturing process whereinsolenoid actuators are joined in series, in parallel, or in acombination of series and parallel.

The present disclosure provides a process, system, and apparatus forfabricating a coil from smaller coils arranged parallel to one anotherand electrically wired in parallel to one another.

Various embodiments of the disclosure will be apparent to those of skillin the art upon review of the teachings herein. The various embodimentsof the disclosure, set forth explicitly herein or otherwise ascertainedfrom the teachings herein, may address one or more of the above objectsalone or in combination, or alternatively may address some other objectascertained from the teachings herein. It is not necessarily intendedthat all embodiments be addressed by any single aspect of thedisclosure, even though that may be the case with regard to someaspects. Other aspects of the disclosure may involve combinations of theabove noted aspects of the disclosure. These other aspects of thedisclosure may provide various combinations of the aspects presentedabove as well as provide other configurations, structures, functionalrelationships, and processes that have not been specifically set forthherein.

A key application for the disclosure is in robotics, including soft(i.e., compliant) robots. Traditional robotic systems are comprised ofsubstantially rigid elements with rotary joints and localized actuation.A new class of soft robotic systems is rapidly emerging, driven by anumber of performance and application requirements. Due to theirintrinsic compliance, soft robots can be more suitable than rigid onesto work safely and collaboratively with and in close proximity topeople. Reliable grasping and manipulation of delicate, flexible, andirregular objects found often in the real world (e.g., tools, fruit on atree) without damage has proven challenging to rigid robots; soft robotspromise a more natural and potentially simpler solution to theseproblems. Unlike a rigid robot, a soft robot might be able to contortand contract itself to wriggle through narrow openings, as might beneeded for search and rescue or soldier-assist. Moreover, soft robotscan exploit biomimetic and previously-unavailable modes of locomotion,such as the peristaltic motion of a worm [Seok et al., in publication],enabling navigation through small passageways or irregular terrain. Softrobots can have increased robustness (e.g., to survive drops), lowermass, lower cost, and lower operational noise (e.g., stealthy). Lastly,soft robots can have deformable “skins”, enabling broad-area tactilesensing or even very high resolution visual/tactile sensing (e.g., byincorporating fine particles into the skin surface as in the Gelsight™material (Gelsight, Inc., Waltham, Mass.).

A key challenge of soft robots is being able to practically manufacturerobot components having distributed actuation—soft robots intrinsicallyhave a large number of degrees of freedom, and multiple actuators can beimpractical, costly, and heavy to assemble and interconnect usingdiscrete components—and/or broad-area touch sensing. Indeed, the 2009Roadmap for U.S. Robotics calls for “embedded sensors and actuators insoft materials for robot limbs and bodies” in 10 years to address thischallenge. The disclosure allows for automated, custom, rapid, low-costfabrication without assembly of entire, functional robots and robotsubsystems, including application-specific robots: the unprecedentedcapability to literally print robots. Ultimately, the embedding ofintegrated circuits (microcontrollers, memory, optoelectronics, RFIDcomponents, etc.) and MEMS (microelectromechanical) devices needed inrobotic systems can provide even greater functionality.

The disclosure is also applicable to many other fields including highlydexterous, lifelike prosthetics; minimally-invasive surgicalinstruments; microfluidic devices with built-in pumps, heating elements(e.g., for PCR), mixers and filters (which may incorporate fibers (e.g.,glass) as elements), fiber optic probes, and electrodes (e.g., forelectrophoresis); bespoke wearable and stretchable electronics withintegrated physiological sensors and communications; small UAVs withbuilt-in radar (e.g., phased array radar) and shape-morphing wings, andconcealments for surveillance, to name a few. Moreover, the disclosurerelates to a revolutionary packaging approach that can liberateelectronic products from the rigid, planar constraint of printed circuitboards and offer new, flexible, organic, customizable 3-D form factorsin which product and circuit become one, and multiple levels ofconventional packaging are eliminated, reducing size, weight, and costwhile boosting reliability. In addition to wires providing electricaland magnetic properties, other fibrous elements such as fluidic channelsand optical fibers can be incorporated into polymer structuresfabricated according to the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the features and advantages of thepresent disclosure, reference is now made to the detailed description ofthe disclosure along with the accompanying figures and in which:

FIG. 1 is an isometric depiction of a robot limb with distributed, wiredactuators and sensors, able to bend and change length.

FIG. 2 is an isometric cross-section view of a FEAM printhead.

FIG. 3 is a diagram showing transitions between voxel types.

FIG. 4(a) shows a cross-section of the lower portion of a FEAMprinthead.

FIG. 4(b) shows a magnified cross section of the lower portion of a FEAMprinthead.

FIG. 4(c) depicts an isometric view of FEAM printhead capillary,clamp/cutter, and square wire.

FIGS. 5(a), 5(b), 5(c), and 5(d) depict cross-sectional views of a wirecutting process.

FIGS. 6(a), 6(b), 6(c), 6(d), and 6(e) depict cross-sectional views of awire starting and anchoring process.

FIGS. 7(a) and 7(b) show cross-sectional views of a FEAM printheaddispensing polymer (7(a)) and with the printhead purged (7(b)).

FIGS. 8(a) and 8(b) show plan views (i.e., looking down onto the X/Yplane parallel to the layers) of intra-layer junctions (8(a)) and across-sectional elevation view of inter-layer junctions (8(b)).

FIG. 9 shows a front elevation view of apparatus for FEAM.

FIG. 10 Shows a cross-sectional schematic of a plunger type solenoidactuator (PRIOR ART).

FIGS. 11(a) and 11(b) depict two coil architectures in isometric views:stacked planar spiral coils connected in parallel (11(a)) and stackedpairs of spiral coils connected in series (11(b)).

FIG. 12 shows an isometric view of a solenoid plunger formed by stackingtight spirals of bare square ferromagnetic (e.g., nickel) wire.

FIGS. 13(a), 13(b), and 13(c) show plan views of one or two layers of astructure which incorporates encapsulated wires and ECPC.

FIG. 14 depicts a cross-sectional view of a printhead wherein thecapillary tip is below the nozzle.

FIG. 15 depicts a cross-sectional view of a printhead wherein the nozzleaxis is tilted away from perpendicular to the extrudate.

FIG. 16 provides a cross-sectional view of a printhead wherein thecapillary is tilted away from perpendicular to the extrudate.

FIG. 17 shows a cross-sectional view of a printhead wherein polymer andwire descend a distance below the nozzle before contacting the previouslayer.

FIG. 18 depicts a cross-sectional view of a printhead wherein a ramp isprovided to direct extruded polymer and wire.

FIG. 19 is a cross-sectional view of a printhead wherein a curve tube isprovided to direct extruded polymer and wire.

FIG. 20 depicts a cross-sectional view of a printhead wherein a curvedcapillary extension extends below the nozzle.

FIG. 21 depicts a cross-sectional view of a printhead comprising amoveable cutting tube and anvil.

FIG. 22 depicts a cross-sectional view of a polymer filament passingthrough a tube that provides sealing.

FIG. 23 shows a cross-sectional view of a rotating tube that drawsfilament into it.

FIGS. 24(a), 24(b), 24(c), and 24(d) show in cross-sectional views aseries of steps in anchoring a wire by altering the tilting axis of aprinthead.

FIGS. 25(a) and 25(b) depict cross-sectional (25(a)) and plan (25(b))views of wire loops which extend beyond the boundaries of the extrudate.

FIGS. 26(a) and 26(b) show cross-sectional views of dome-like actuators.

FIGS. 27(a) and 27(b) show cross-sectional views of dome-like actuatorsarranged in series and in parallel.

FIG. 28 shows a plan view of an actuator comprising tensioned elastomerstrips.

FIGS. 29(a) and 29(b) are cross-sectional elevation views depicting twocapillaries that are external to the nozzle in some embodiments.

FIGS. 30(a), 30(b), and 30(c) depict cross-sectional elevation views ofan external capillary used in some embodiments and similar to that ofFIGS. 29(a) and 29(b).

FIG. 31 is a cross sectional view of feeding of filaments.

FIGS. 32(a) and 32(b) illustrate a wire feeding mechanism.

FIGS. 33(a), 33(b), 33(c), 33(d), and 33(e) illustrate a wire feedingand cutting mechanism.

FIGS. 34(a) and 34(b) depict an apparatus for cutting wire.

FIG. 35 depicts an approach used in some embodiments for cutting wireissuing from an external capillary.

FIG. 36 depicts a nozzle.

FIG. 37 depicts a cross sectional elevation view of an embodimentwherein an angled tunnel is provided in the nozzle to serve as acapillary to deliver the filament.

FIGS. 38(a), 38(b), 38(c), and 38(d) depict aspects of printheads usedin some embodiments wherein the axes of the capillary and nozzle aresubstantially parallel.

FIG. 39 depicts a plan view sequential schematic illustrating thedeposition of an extrudate along a curved, U-shaped path.

FIGS. 40(a), 40(b), 40(c), and 40(d) depict in plan view the behavior ofan external capillary.

FIGS. 41(a), 41(b), 41(c), and 41(d) illustrate a nozzle moving along astraight line and curved lines.

FIG. 42 is an isometric schematic view of apparatus used in someembodiments wherein the printhead moves in the Z direction.

FIG. 43 depicts a cross-sectional elevation view of a printhead.

FIG. 44 depicts a plan view of a printhead.

FIGS. 45(a) and 45(b) depict plan views of printheads having multipleexternal capillaries delivering multiple filaments.

FIGS. 46(a), 46(b), and 46(c) are plan views illustrating a rectangularnozzle orifice.

FIGS. 47(a) and 47(b) are plan views depicting another orifice used insome embodiments that is not rotationally symmetric.

FIG. 48 illustrates in plan view a junction used in some embodiments inwhich the wires are parallel.

FIG. 49 depicts a cross-sectional elevation view of a printhead.

FIG. 50 depicts a cross-sectional elevation view of a printheadcomprising a double-drum extruder intended for use in FDM of softelastomers.

FIGS. 51(a) and 51(b) depict cross-sectional isometric views of acentrifugal extruder.

FIG. 52 depicts an isometric view of a wire that is “stapled”.

FIGS. 53(a), 53(b), 53(c), 53(d), and 53(e) depict cross-sectionalelevation views of an anchoring method.

FIGS. 54(a), 54(b), 54(c), and 54(d) depict cross-sectional elevationviews of an anchoring method.

FIGS. 55(a) and 55(b) depict two cross-sectional elevation views of afabricated object.

FIGS. 56(a) and 56(b) depict an isometric view of a curved 3-Dstructure.

FIGS. 57(a), 57(b), 57(c), 57(d), and 57(e) depict elevation views of amethod and apparatus used in some embodiments of magnetizing PMPCs.

FIGS. 58(a), 58(b), and 58(c) depict cross-sectional elevation views ofa method for embedding an integrated circuit.

FIGS. 59(a), 59(b), and 59(c) are cross-sectional elevation views ofFIGS. 58(a), 58(b), and 58(c).

FIG. 60 depicts an isometric view of a discontinuous Z-axis coil.

FIG. 61 depicts an isometric view of a continuous helical coil.

FIGS. 62(a), 62(b), 62(c), 62(d), and 62(e) show cross-sectionalelevation views of steps for fabricating a continuous helical coil.

FIGS. 63(a), 63(b), 63(c), 63(d), 63(e), and 63(f) show cross-sectionalelevation views of steps of an alternative approach for fabricating acontinuous helical coil.

FIG. 64 is a plain view of an external capillary and nozzle.

FIG. 65 is an isometric view of capillary whose axis is substantiallyparallel to the nozzle axis.

FIGS. 66(a), 66(b), 66(c), and 66(d) depict a coil which has beenfabricated discontinuously.

FIGS. 67(a), 67(b), and 67(c) depict in cross-sectional elevation viewstwo approaches to electrically connect wires from one layer to another.

FIGS. 68(a) and 68(b) are cross-sectional elevation views of a group oflayers comprising wires which are at least partly surrounded by ECPC.

FIGS. 69(a), 69(b), 69(c), 69(d), and 69(e) depict in cross-sectionalelevation views an approach to creating junctions between two layers inwhich ECPC.

FIGS. 70(a), 70(b), and 70(c) depict a specialized pounce wheelarrangement for encapsulated filament.

FIG. 71 is a cross-sectional elevation view depicting a printheadfurnished with a gas inlet.

FIG. 72 depicts an isometric view of an extrudate in which isencapsulated a wire that has a helical form.

FIG. 73 is an isometric view of a capacitor produced using wireencapsulated at least partially in a dielectric.

FIG. 74 depicts an isometric view of a spiral inductor.

FIG. 75 is a plan view (or an elevation view) showing a resistor.

FIGS. 76(a), 76(b), 76(c), and 76(d) depict cross-sectional elevationviews of extrudates.

FIGS. 77(a), 77(b), 77(c), and 77(d) depict nozzles used in magneticextrusion and extrudates produced.

FIGS. 78(a) and 78(b) depict cross-sectional elevation views of aprinthead “hot end”.

FIGS. 79(a) and 79(b) depict a method of stress-decoupling a junction.

FIGS. 80(a) and 80(b) depict structures that are poorly supported butwhich may be built using cooling.

FIGS. 81(a), 81(b), and 81(c) depict a cooling apparatus.

FIGS. 82(a) and 82(b) depict structures being fabricated using cooling.

FIG. 83 depicts a printhead incorporating a rotating cooling tube.

FIGS. 84, 85, 86, 87, 88, 89, 90, 91, 92, 93 depict an extrusion-basedprinthead able to extrude soft filaments.

FIG. 94 shows a wire embedding head incorporating cooling and/orheating.

FIGS. 95(a) and 95(b) show wheels used for wire embedding.

FIGS. 96(a), 96(b), 96(c), 96(d), 96(e), and 96(f) show an approach towire embedding.

FIGS. 97(a) and 97(b) show wire embedded at variable depths.

FIGS. 98(a), 98(b), 98(c), 98(d), 98(e), 98(f), 99, 100, and 101 show avariety of junctions.

FIGS. 102(a), 102(b), 102(c), and 102(d) show a wire cutting and feedingapparatus.

FIGS. 103(a), 103(b), 103(c), 103(d), 103(e), 103(f), 103(g), 103(h),104(a), 104(b), 104(c), 104(d), 104(e), 104(f), 104(g), 104(h), 105(a),105(b), 105(c), 105(d), 105(e), 105(f), 105(g), 105(h), 105(e′),105(f′), 105(g′), 105(h′), 105(i′), 105(e″), 105(f″), 105(g″), and105(h″) depict methods for printing with wire and extruded material.

FIGS. 106(a) and 106(b) show an approach to integrating an electronicdevice with a fabricated structure.

FIGS. 107(a), 107(b), 107(c), 107(d), and 107(e) show an approach toincorporating closely-spaced wires.

FIGS. 108(a), 108(b), 108(c), and 108(d) show a method for determiningtoolpaths for extruded material, wire, and conductive material.

FIGS. 109(a), 109(b), 109(c), 110(a), 110(b), 110(c), 110(d), 110(e),110(f), 110(g), 111(a), 111(b), 111(c), 111(d), 112(a), 112(b), and112(c) illustrate coaxial-type fabricated structures and methods ofmanufacture

FIGS. 113(a) and 113(b) show different types of junctions.

FIGS. 114(a), 114(b), 114(c), and 114(d) depict a method of applyingconductive material to form junctions.

FIGS. 115(a), 115(b), 115(c), 115(d), 115(e), 115(f), 116(a), 116(b),116(c), and 116(d) show methods for incorporating thick fibers.

FIGS. 117(a), 117(b), and 117(c) illustrate methods for managingdifferential size change.

FIGS. 118(a) and 118(b) depict a multiple nozzle printhead.

FIGS. 119(a), 119(b), and 119(c) show methods for producing curved fibershapes.

FIGS. 120(a), 120(b), and 120(c) depict a printhead with a variable sizeorifice.

FIGS. 121(a), 121(b), 121(c), 121(d), and 121(e) show a method forincreasing bonding between layers.

FIG. 122 illustrates a fiber with a particular shape.

FIGS. 123 and 124 illustrate a method for producing a multi-layer coil.

FIG. 125 depicts a method for welding wire.

FIGS. 126(a), 126(b), 126(c), 126(d), 126(e), 126(f), 126(g), 126(g′),127(a), 127(b), 127(c), 127(d), 128(a), 128(b), and 128(c) show methodsfor integrating devices into fabricated objects.

FIGS. 129(a), 129(b), 130(a), 130(b), 131(a), 131(b), 132, 133(a),133(b), and 133(c) show fluidic devices, some incorporating fibers.

FIGS. 134(a) and 134(b) depict a drive belt fabricated with integratedreinforcement.

FIGS. 135(a) and 135(b) illustrate monolithic electromagnetic devices.

FIGS. 136(a), 136(b), 136(c), 137(a), 137(b), and 137(c) depict electricmotors.

FIGS. 138(a), 138(b), 138(c), 138(d), 138(a′), 138(b′), and 138(c′)illustrate a wire cutting apparatus and method.

FIGS. 139(a), 139(b), 139(c), 139(d), 139(e), 139(f), 139(g), and 139(h)depict a fiber feeder/cutter.

FIG. 140 shows the relative placement of nozzle and capillary in someembodiments.

FIGS. 141(a), 141(b), 141(c), 141(d), 141(e), and 141(f) depict asequence for cutting wire.

FIGS. 142(a), 142(b), 142(c), 142(d), 142(e), 142(f), and 142(g) depicta method for breaking wire.

FIGS. 143(a), 143(b), 143(c), and 143(d) show a nozzle that may be usedfor side-by-side wire laying.

FIGS. 144(a), 144(b), 144(c), 144(d), 144(e), 144(f), and 144(g) depicta fiber feeder/cutter.

FIGS. 145(a), 145(b), 145(c), and 145(d) illustrate an extruder.

FIGS. 146(a), 146(b), 146(c), 146(d), 146(e), 146(f), 146(g), 146(h),146(i), 146(j), 146(k), 146(l), 146(m), and 146(n) depict a coil havinga thick wall and a method of fabrication.

FIGS. 147(a), 147(b), 147(c), 147(d), 148(a), 148(b), 148(c), 148(d),and 148(e) depict an apparatus for soldering.

FIGS. 149(a), 149(b), and 149(c) show junctions between wires.

FIG. 150 depicts apparatus for storing and dispensing conductivematerial.

FIGS. 151(a), 151(b), 151(c), 152(a), 152(b), 152(c), 153(a), 153(b),154(a) and 154(b) show a stretchable circuit element.

FIGS. 155(a), 155(b), and 155(c) depict approaches to stabilizing acapillary.

FIGS. 156(a), 156(b), 156(c), and 156(d) show an approach to filling acavity with a material.

FIGS. 157(a), 157(b), 157(c), and 157(d) depict a method for dispensingobjects into a structure.

FIGS. 158(a) and 158(b) show a printable valve.

FIGS. 159(a), 159(b), 159(c), 160(a), 160(b), 160(c), 161(a), 161(b),161(c), 161(d), 162(a), 162(b), 162(c), 163(a), 163(b), 164(a), 164(b),and 165 depict fluidic actuators.

FIG. 166 shows an arm using fluidic actuators.

FIG. 167 depicts an approach to fabricating a coil.

FIGS. 168(a), 168(b), 168(c), 168(d) 168(e), 168(f), 168(g), 168(h),168(i), and 168(j) show an apparatus for feeding and cutting wire.

FIGS. 169(a), 169(b), 169(c), 169(d), 169(e), and 169(f) depict anapparatus for feeding wire.

FIGS. 170(a), 170(b), and 170(c) show a method for making a coil.

FIGS. 171(a), 171(b), 171(c), 171(d), 171(e), and 171(f) depict a softarm with embedded electrodes.

FIGS. 172(a), 172(b), 172(c), 172(d), and 172(e) show an apparatus forfabricating multi-material devices.

FIGS. 173(a), 173(b), and 173(c) show an approach to making electricalcontact.

FIGS. 174(a), 174(b), 174(c), 174(d), 174(e), 174(f), 174(g), and 174(h)depict a soft robot.

FIGS. 175(a), 175(b), 175(c), 175(d), 175(e), and 175(f) show anapparatus for feeding wire.

FIGS. 176(a), 176(b), and 176(c) depict a method for producing exposedwire.

FIG. 177 shows a method for incorporating solid objects.

FIGS. 178(a), 178(b), 178(c), 178(d), and 178(e) depict a method forextracting toolpath data from a file.

FIGS. 179(a), 179(b), 179(c), and 179(d) show a wire segment feeder.

FIGS. 180(a), 180(b), 180(c), 180(d), 180(e), 180(f), 180(g), 181(a),181(b), 181(c), 181(d), 181(e), 181(f), 181(g), and 181(h) show steps inthe operation of a wire segment feeder.

FIGS. 182(a), 182(b), 182(c), 182(d), 182(e), 182(f), 182(g), 183(a),183(b), and 183(c) depict approaches to increase metal content.

FIGS. 184(a), 184(b), 184(c), 184(d), 184(e), 184(f), 184(g), and 184(h)show approaches to incorporating flat wire.

FIGS. 185(a), 185(b), 185(c), 185(d), and 185(e) depict a rotary motor.

FIGS. 186(a) and 186(b) show an approach to fabricating a motor pole.

FIGS. 187(a), 187(b), 187(c), 187(d), 187(e), 187(f), 187(g), and 187(h)depict an apparatus for dispensing blocks.

FIG. 188 shows a 3-D printed hybrid electronic module.

FIGS. 189(a), 189(b), and 189(c) depict an approach to designingelectronic modules.

DETAILED DESCRIPTION

While the making and using of various embodiments of the presentdisclosure are discussed in detail below, it should be appreciated thatthe present disclosure provides many applicable inventive concepts thatcan be embodied in a wide variety of specific contexts. The specificembodiments discussed herein are merely illustrative of specific ways tomake and use the disclosure and do not delimit the scope of thedisclosure.

To facilitate the understanding of this disclosure, a number of termsare defined below. Terms defined herein have meanings as commonlyunderstood by a person of ordinary skill in the areas relevant to thepresent disclosure. Terms such as “a”, “an” and “the” are not intendedto refer to only a singular entity, but include the general class ofwhich a specific example may be used for illustration. The terminologyherein is used to describe specific embodiments of the disclosure, buttheir usage does not delimit the disclosure, except as outlined in theclaims.

AM (Additive Manufacturing, a.k.a., 3-D Printing) is a proven approachto rapid, layer-by-layer fabrication of complex 3-D parts with internalfeatures, and mechanical devices with multiple moving parts requiring noassembly. The present disclosure is intended to achieve a “holy grail”of AM: namely, to provide a truly multi-material AM process that canfabricate functional electromechanical devices. The disclosure wouldgreatly extend AM to enable automated fabrication of multi-material,multi-functional components and devices having embedded actuators,sensors, 3-D circuitry, and elements such as resistors, capacitors,inductors, and antennae.

The potential impact of the disclosure is in providing a new means ofmonolithically producing fully-customized functional components andsystems without the need for assembly, directly from digital data. Inthe semiconductor industry, monolithic fabrication has made possible theintegrated circuit. At the macro scale—and incorporating mechanical, notjust electrical elements—monolithic fabrication can also have a hugebenefit, reducing cost while increasing reliability and quality, andenabling products impossible with traditional approaches. The methodsand apparatus of the disclosure incorporate materials such as metal wireand conductive composites into a polymer matrix as a structure or deviceis built up, one layer at a time. More specifically, it provides forsimultaneous deposition of conductive and/or ferromagnetic wirestogether with polymer such as a pure polymer (e.g., an elastomer) or anelectrically conductive polymer composite (ECPC) composed of polymer andconductive filler particles, or a magnetic polymer comprisingferromagnetic or permanently-magnetic particles in a polymer matrix. Theability to controllably deposit these multiple materials providesenormous flexibility in creating mechatronic structures with embeddedelectromagnetic elements.

Unlike the SpoolHead system described hereinabove, the FEAM technologyof the present disclosure can achieve the same results as SpoolHead, butsolves a number of fundamental problems including 1) difficulty ofbonding wire securely to polymer (required for self-feeding of wire andmaking sharp turns), 2) low throughput/slow processing, and 3) lack of aviable solution to intra- or inter-layer interconnects. In addition,such systems would have trouble completely encapsulating wire andspacing wires closely without shorting, can only be used withthermoplastic materials, and may involve costly components such asultrasonic transducers and power supplies. These limitations renderSpoolHead and its derivatives impractical; FEAM is far more practical,versatile, and reliable.

To take full advantage of the flexibility offered by soft robotsrequires the integration of sensing and actuation elements andcircuitry/electrical wiring directly into the robot structure (e.g.,FIG. 1). Indeed, in the extreme case of a robotic limb without any rigidsupport (e.g., a tentacle), distributed actuation must be integratedinto the element during fabrication (similar to the muscles in squidtentacles) for the device to function at all. To address thesechallenges, the disclosure provides a new multi-material AdditiveManufacturing (AM, a.k.a 3-D printing) method for rapidly, economically,automatically, and flexibly manufacturing complex 3-D structures,devices, components, systems, products, and assemblies: to produce bothprototypes and functional, usable devices. Among the systems that can befabricated using FEAM are soft robot components with embedded,distributed actuation, sensing, and circuitry/interconnect (e.g., powerand signal), produced without the need for assembly. FEAM generatesactive electromechanical structures, is driven directly by computeraided design (CAD) data, requires no tooling, and uses low-costmaterials. FEAM enables complex geometries as well as distributedelements and material combinations and arrangements that in many casesare impossible to produce using the prior art. FEAM can print standalonemechatronic devices, robot parts, integrated subsystems, entire robots,packaging systems, and entire electronic devices.

FEAM fabricates components in layers by extruding dielectric andconductive polymer along with an embedded wire core. The ability tocreate heterogeneous structures using both dielectric andelectromagnetic materials in an AM processes allows for monolithicfabrication of actuators and sensors embedded within the structure beingfabricated. The result is a “smart”, multifunctional, active materialthat can dynamically modulate its shape and sense its environment. WithFEAM, actuators and sensors can be distributed throughout the volume ofthe fabricated device, located virtually anywhere and built in virtuallyany shape. Among its other benefits, distributed fabrication alsoenables localization of actuation, sensing, and processing(computation/control/memory). Thus, devices can be more modular and ifprovided with well-defined interfaces, component re-use using componentlibraries is more easily achieved. Thus a robot can be designed using alibrary of modules that provide the desired actuation and sensing, andprocessing capabilities, with all modules built together monolithically.AM (Additive Manufacturing, a.k.a., 3-D Printing) is a proven approachto rapid, layer-by-layer fabrication of complex 3-D parts with internalfeatures, and mechanical devices with multiple moving parts requiring noassembly. Additive Manufacturing typically produces prototypes,production parts, and tooling directly from raw materials based on CADmodels by depositing successive layers of material (e.g., polymer ormetal) to build up a 3-D structure. Since there is full access to bothinternal and exterior regions as layers are formed, AM can make productsotherwise impossible to manufacturable. AM can make parts in mere hoursusing a compact, self-contained machine. It usually requires no molds,patterns, or masks, produces little waste, often yields ready-to-useproducts, and allows an unlimited degree of customization at noadditional cost. Nonetheless, AM has achieved only a fraction of itspotential. In particular, current processes are unable to producefunctional mechatronic devices since AM uses homogeneous materials,whereas mechatronic devices must contain elements that are dielectric,conductive, and often, magnetic.

FEAM is based on the Fused Deposition Modeling (FDM) process introducedby Stratasys (Eden Prairie, Minn.). In FDM, a thermoplastic polymerfilament is fed by rollers into the heated liquefier tube of a printheadwhere it is melted and extruded from a nozzle. The head moves accordingto an X/Y toolpath under computer control, based on the calculatedcross-section of the structure to be fabricated, laying down polymerextrudates that form the perimeter, top and bottom surfaces, andinterior “fill” of a layer. FDM has several primary benefits: 1)fabrication using robust engineering polymers, 2) low cost, and 3)ability to produce multiple-component assemblies of moving parts.

FEAM greatly extends FDM, integrating the deposition of conductive wire(or other material in filament/elongated form, hereinafter “wire”) intothe process. In some embodiment variations, the wire is ferromagnetic,e.g., to allow for fabrication of elements of electromagnetic devices.In some embodiment variations, FEAM also integrates metalparticle-filled polymer composite into the FDM process.

FEAM allows, for example, the fabrication of robot limbs with built-in,distributed actuators (electromagnetic, capacitive, etc.) and afull-surface tactile sensing “skin”. Such a limb can support amulti-fingered hand—also built with FEAM—that manipulates objects;meanwhile, four such limbs can serve as robot legs. FEAM can produceworm- and snake-like robots that move like their biological cousins,swimming robots, shape-changing robots, and other novel configurations.Affordable, patient-unique disposable surgical and interventional robotswith many degrees of freedom that allow access to deep brain tumorsthrough a small incision are also enabled by FEAM.

FEAM enables robot components to be produced in hours. Custom,application-specific component designs in 3-D CAD are manufacturablewithout tooling, using an automated machine, and from low-costmaterials.

Robots are typically assembled from discretely-manufactured and packagedcomponents that require interconnection and are often costly and bulky.Therefore is it normally impractical to incorporate a large number ofactuators and sensors. Monolithic fabrication of components and wiringusing FEAM allows 10s-100s of actuators and sensors to be “built in” torobot body structures as they are made. Distributed actuation enablesmore degrees of freedom [Walker et al., 2005], increased dexterity, morecomplex motions (e.g., facial expressions for humanoids [Tadesse et al.,2011], new modes of locomotion, adaptive and shape-changing structures,dynamically-tunable stiffness, and redundancy. It allows largedisplacements and large forces to be generated from short-stroke andsmall actuators, respectively. Moreover, the ability to locate anactuator close to the point of action frees up “real estate” otherwiseoccupied by linkages, cables, etc. Nonetheless, embedded wires and otherfibers (e.g., Kevlar, carbon) may be used as “tendons” enabling remoteactuation (e.g., fingers of a robot or prosthetic hand may be operatedby actuators located in the palm and connected to the fingers by suchtendons. In some embodiments, the tendon itself is the actuator (e.g.,if made from a shape memory alloy such as nickel-titanium). To allowfree movement of tendons within a structure, they may be formed inchannels free of matrix material, or be only surrounded by elastomers,or comprise fibers with non-stick coatings, or comprise fibers withintubes which are co-deposited using FEAM, etc.

In the case of a flexible matrix material surrounding them, tendons mayadhere to the matrix material. However, when the matrix is more rigid,and even in some cases when it is not, it may be best for the tendon toslide within the matrix material (i.e., not be adhered to it). Toachieve this, in some embodiments rather than encapsulating fiber alone,a tube containing a fiber (or into which a fiber can later be inserted)is encapsulated instead. In some embodiment variations, the fiber may bebraided, which may facilitate pushing and twisting it in regions thatare tortuous). In some embodiment variations, the tube has a lowcoefficient of friction at least on its inside (e.g., it may be made ofPTFE). In other embodiments, a non-adhering fiber may be achieved bychoosing a difficult-to-bond material for the fiber, or coating it withsuch a material (e.g., PTFE), or by exposing the fiber to a bondinginhibitor (e.g., a liquid or vapor) such as an oil just beforeencapsulating it in matrix material. In some embodiments, the adhesionof fiber to matrix material that may normally occur may be brokenmechanically during the fabrication process or afterwards. For example,the fiber can be pulled manually or by an actuator after or duringfabrication; if the tensile strength exceeds the adhesion strength, thefiber will be broken free and be able to slide within the matrixthereafter. The wire may also be fed more slowly than the X/Y stagetangential speed, thus applying tension to the wire. Mechanicaldisruption of adhesion can be achieved during wire laying in FEAM byprinting in short steps as follows: Matrix and fiber can be printed oneshort segment at a time, with the fiber pulled periodically (e.g., bystopping the feeder/cutter feed rollers and advancing the X/Y stages) tobreak it free of the matrix.

With regard to sensing, the ability to build a component with sensorsdistributed throughout (e.g., near the surface for tactile sensing)promises to imbue robots with high spatial resolution capabilities thatbegin to emulate living organisms. FEAM also enables complex 3-D wiringnetworks and dense connectors with dozens of I/O so that distributedelements can be connected and interfaced to controllers, power, etc.

With FEAM, actuators, sensors, and wiring—as well as any discretedevices incorporated while building—can be encapsulated by polymer atvirtually no additional cost in material or processing time. As suchthey will be unable to delaminate and will be protected from hazardssuch as mechanical forces that can cause distortion or fracture,moisture (e.g., humidity, rain, sweat), dust, electromagneticinterference (built-in shields and Faraday cages can be provided), andcorrosive fluids. Because the conductive material is normally surroundedby polymer on all sides, adhesion between the conductive material andthe polymer is less of an issue than with surface metallizations, whichcan peel away. Moreover, unlike attempts to metalize the surface of AMparts through a separate operation, the topography of the solidifiedpolymer surface is irrelevant, and no smoothing/bonding layer isrequired to allow metallization.

Thus, the present inventors have developed a novel FEAM that for thefirst time enables the additive manufacturing of multi-material, activestructures and devices such as robots, which comprise 3-D electricalcircuits, actuators, sensors, and other components. A key challenge inintegrating distributed actuators and sensors throughout a robot body orcomponent—as well as for other active devices—is providing electricallyconductive pathways through a dielectric material. Common methods ofachieving conductivity such as low-temperature solders and conductiveinks (e.g., containing silver, copper, gold, platinum, nickel, etc.)have issues with high-temperature curing operations, adhesion with thepolymer, throughput, limited geometries, and sophisticated equipmentrequired to implement. In lieu of these approaches—and far morecompatible with AM processes—is FEAM's use of conductive composites andfibrous conductors (i.e., wires).

Epoxy and silicone conductive adhesives are widely available, andthermoplastic conductive adhesives for flip chip applications are in use[Gilleo, 2000]. By adding conductive particles at sufficientconcentration to thermoplastic it is possible to produce an electricallyconductive polymer composite (ECPC). At low concentrations, the additivedoesn't change the electrical properties of the polymer matrixsignificantly because the particles are dispersed and non-contacting. Asthe concentration increases, a sharp increase in conductivity iseventually achieved at the “percolation threshold”, when enoughparticulate material is incorporated that conductive junctions areformed between neighboring particles/particulate agglomerates andconductive pathways are formed throughout the composite matrix [Aneli etal., 2012; Huang, 2002]. Further increases in the concentration ofparticulate above the threshold will increase bulk conductivity, but ata much lower rate.

Conductive particles useful in FEAM include those comprised of nickel,silver, gold, carbon, and copper. Such particles can have multipleforms, e.g., solid metal, metal-coated polymer, metal-coated ceramic,and metal-coated glass. Particles may be micro-scale (e.g., averagesizes in the range of 5-50 μm) or nano-scale (e.g., average sizes <1μm). As an example, small conductive nickel and silver-coated nickelparticles are available from Novamet Specialty Products Corporation(Wyckoff, N.J.), and silver-coated nickel, iron, and hollow glassmicrospheres are available from Potters Industries LLC (Malvern, Pa.).

If the polymer is an elastomer (e.g., for a soft robot), then additionof particulate to the matrix generally would make the material stifferand more brittle as particulate concentration is increased. Moreover,the conductivity of ECPC is far lower than that of the pure additivematerial (typically by a factor of 103-108) due mostly to loweredconductive area and inter-particle electrical resistance [Ruschau etal., 1992]. Even some of the highest-conductivity ECPC adhesives (e.g.SEC1244 (Resinlab, Germantown, Wis.): resistivity ˜6×10⁻⁴ ohm-cm) areover 200 times less conductive than annealed Cu. Hence, use of ECPC forcreating long conductive pathways would introduce excessive electricallosses and associated heating, as well as potentially degrading themechanical properties of the elastic structure. Moreover, long pathwaysof ECPC may be subject to strain-induced conductivity changes orde-percolation, especially when supported by a soft elastomer matrix,whereas localized regions of ECPC (in junctions) can be more easilydecoupled from stress that may induce excessive strain and reduceperformance. Instead, FEAM uses metallic wires embedded (e.g.,coaxially) within the polymer (creating a “coaxial composite”) for themajority of the conductive pathways, limiting, in some embodimentvariations, the use of ECPCs to creating electrical junctions/joints,which are relatively small. In some embodiments, the process may involvejunctions that are do not provide electrical functionality (e.g., if thefiber is not conductive) but provide other functionality such asmechanically coupling stress from one fiber to another, providing anoptical junction between optical fibers, etc.

To form 3-D structures from a plurality of polymer extrudates with metalwire embedded substantially coaxially in selected regions, and (in someembodiment variations) to use ECPC to form electrical junctions, FEAMleverages several key technologies: 1) FDM using thermoplastic polymersor other solidifiable materials such as thermoset polymers; 2) in someembodiments, ECPCs; and 3) in some embodiments, crosshead extrusion forwire coating. In the case of FEAM fabricating soft structures,thermoplastic or thermoset elastomers are used as the solidifiablematerial.

In addition to the advantages mentioned above, FDM has the ability touse a range of thermoplastic materials, uses a vector depositionapproach (vs. raster) that is intrinsically more compatible withincorporation of wire, and can include voids in structures, which can beused to adjust elastic modulus and other properties. However, comparedwith FDM, FEAM requires apparatus with a novel printhead, novel process,novel control software, and novel material supply.

Crosshead extrusion is the standard process for insulated wireproduction. Molten polymer from an extruder enters a side port whilewire is fed perpendicularly through the head: the polymer envelopes thewire exiting from the lumen of a capillary. Polymer and wire then passthrough a die that establishes the outside diameter of the coated wire,and the polymer jacket is allowed to solidify [Drobny, 2011].

While ECPCs are at present a poor choice for general wiring due to thelong conductive pathways often required, in some embodiment variationsthey are highly advantageous for creating electrical junctions. Toproduce 3-D devices and provide power and signal paths to embeddedcomponents, electrical junctions are in general needed both betweenwires within the same layer (intra-layer) and between wires in adjacentor separated layers (inter-layer). A number of methods are available tocreate such junctions. In some embodiment variations, wires may bebrought closely together and soldered or brazed. In other embodimentvariations, wires may be pressed together and ultrasonically orthermosonically bonded. In yet other embodiment variations, wires may bewelded (e.g., by laser welding or resistive welding). In yet otherembodiment variations, wire may be simply mechanically placed intocontact with other wire, crimp other wire, or be wound around orentangled with other wire, to form a junction that remains robustlyconductive and tolerant to deformation due to the wires being “potted”in and thus captured by surrounding polymer. Or, a “free air ball” (FAB)may be formed on the wire, e.g., using a variant of “electronicflame-off”, a spark technique used in semiconductor ball bonders [Harman1997], such that the FAB occupies the full width and/or height of theextrudate; this could make contact with a FAB in an adjacent extrudate,forming a junction.

Because it doesn't require contact or bonding pressure between wires oraccurate alignment of wires, readily accommodates different sizes andcross-sectional shapes of wire, can produce multiple-layer/multiple-wireconnections (by spanning the entire extrudate width and/or height),doesn't require perfectly-clean wires, and can create junctions at anylocation along a wire (not merely at the ends), the use of ECPC to formjunctions is in some embodiment variations particularly preferred.Moreover, ECPCs allow external components such as packaged ICs to beconnected by pushing their leads through the ECPC (if the ECPC is softenough, or the leads are heated), and enable magnetic cores andarmatures (e.g., made from nickel wire such as Ni 200, Ni 201, or Ni205) and/or nickel powder-filled ECPC, or pure ECPC) and capacitorplates. Other elements which could be made using FEAM with the aid ofdeposited ECPC include variable-resistance resistors, force and pressuresensors, temperature sensors, heat sinks, heat pipes, and heatconduction structures. Junctions can be formed by embedding wires in aconductive matrix of deposited ECPC that establishes conductive pathwaysbetween them. While the resistivity of ECPCs is much higher than that ofwire, the distance between wires in the junction is very short, soexcellent junction resistance can in principal be obtained (e.g., ˜0.1ohm for a 1 mm-long junction with wires separated by 250 μm). Effectiveuse of ECPC in FEAM requires judicious selection of particulatematerial, concentrations, and composite preparation. Percolation andconductivity in ECPCs has been studied extensively for differentpolymers and additives, with a focus on carbon black because of cost andthe lack of an insulating oxide layer [Huang, 2002]. A number of factorscan affect the percolation threshold in both hard polymers andelastomers, including the relative affinity of the particulate andpolymer, shape and size of the particulate additive, and preparation ofthe composite material [Huang, 2002; Ruschau and Newnham, 1992; Kalyonet al., 2002; Bayer et al., 1988; Ezquerra et al., 1988]. Regardingcomposite preparation, degree of mixing and forming method (extrusionvs. compression molding) can have an important effect on percolation andconductive properties. A certain level of mixing is required todistribute the conductive filler throughout the matrix, but over-mixingcan increase the minimum concentration of conductive additive requiredfor percolation because the additive agglomerates are broken down andthe particulates become spaced too far apart to form conductive chainswithout increasing concentration [Kalyon et al., 2002]. Mixing, e.g.,using a single screw extruder, in some cases may be enhanced by usingpolymer that is more finely divided (e.g., cryogenically-ground powderor granules) than standard pellets. If the composites are injectionmolded, shear can redistribute the particles and break downagglomerates, affecting the conductive properties across high shearregions [Bayer et al., 1988; Ezquerra et al., 1988].

While general observations about electrical properties and basicmechanical properties (e.g., increased stiffness with higher solidsloading) of ECPCs hold true for both hard polymers and elastomericcomposites, composites based on elastomers present additionalconsiderations. Even with the effect of particulate on mechanicalproperties, strains of several hundred percent are still achievable withtypical conductive elastomeric composites, and filler content may havevery little effect on elongation limit [Sau et al., 1997; Flandin etal., 2001]. With such large strains possible, however, the structure ofthe conductive chains in the composite can change during loading,causing changes in the electrical conductivity during strain, or evenirreversible “de-percolation” if the strain becomes too large [Flandinet al., 2001; Li and Shimizu, 2009]. In some embodiment variations,junctions may be “shielded” from excessive loads that would compromiseelectrical behavior through proper design, incorporation of strong andrigid materials that handle the stress, decoupling of stress as in FIGS.79(a), 79(b), etc. In some embodiment variations, the effect of strainon electrical conductivity may be mitigated by providing higher fillerloading that improves electrical properties but may compromisemechanical properties, especially of elastomers. In any case, ECPCmechanical properties often will not dramatically influence overallstructure behavior since ECPC is localized at junctions. ECPC regionscan also be specially designed and formulated to serve as sensitivesensors for displacement, force, and pressure.

It may be advantageous in some embodiments to blend polymers with morethan one conductive additive to create ECPCs with desirable mechanicalproperties and robust electrical properties. The different conductiveadditives may differ substantially in size and/or shape. For example,conductive spherical particles with diameters of a few microns orsmaller may be used together with larger (greater than 10 microndiameter) conductive spherical particles, or fibrous conductingparticles (with large aspect ratio) may be used together with sphericalparticles greater than 10 μm in diameter. Utilizing smaller particles,and/or particles with large aspect ratio, provides geometric variabilitythat can help fill the gaps between larger spherical particles,achieving conductive chains within the material at lower overallconcentrations, and maintaining conductivity during larger strains[Kyrylyuk et al., 2011].

The polymer used to formulate ECPC may be the same polymer as that usedto fabricate the object in general, or it may be a different polymerthat is compatible (e.g., there is mutual adhesion andcross-contamination is not problematic). The conductive particulateadditive may be a number of materials (e.g., silver, silver-coated glassspheres (hollow or solid), carbon black, nickel, silver-coated nickel)and range in size from nanoscale (sub 1 μm) to several microns or tensof microns. If a magnetic material such as nickel is used, the ECPC canbe used to create structures such as cores/armatures for electromagneticactuators and transformers. An example of an elastomer that may be usedwith FEAM is Chronoprene (AdvanSource Biomaterials, Wilmington, Mass.),which is available in a range of hardness, is highly elastic, has highabrasion resistance and durability, and is biocompatible (e.g. used inballoon catheters), making it suitable for medical devices. A variety ofother elastomers may be suitable, however, including Versaflex™ (PolyOneCorporation (Avon Lake, Ohio), Kraton™ (Kraton Performance PolymersInc., Houston, Tex.), Alcryn® (Advanced Polymer Alloys, Wilmington,Del.), Dryflex T (ELASTO, Sweden) and many others. In addition,air-curing or moisture-curing materials can be used, as well asthermoset materials such as silicone (PDMS), e.g., with thermal or UVcuring. Thermoset materials are not subject to distortion or melting athigher temperatures, and may therefore be more stable in situationsrequiring high currents through wiring (e.g., for some shape memoryactuators and electromagnet coils). Moreover, some thermosets, such assilicone, have well-established biocompatibility. For example, to make aflexible implantable lead for neuromodulation, pacemakers, orimplantable cardioverter defibrillators using FEAM, silicone such as aliquid silicone rubber (LSR) formulation may be combined with Pt—Ir wirewhich is exposed in selected areas to form electrode surfaces. Use ofthermosets may also enable in-situ heat treatment of wire (e.g., toanneal it or set its shape, if capable of shape memory), and canfacilitate the use of heating wires or heated fluid channels to generatebubbles in fluids (e.g., to alter stiffness or eject droplets as in someinkjet printheads), activate shape memory polymer materials incorporatedinto the device, induce melting (e.g., of a low melting point polymer orother phase-change material (e.g., wax) that is melted to reducestiffness), etc. Also, self-healing structures may be produced byincorporating conductive wires or other elements which heat materialthat is cracked or otherwise damaged and cause it to reflow, repairingthe damage.

Thermoplastic elastomers are well-suited as structural polymers forbuilding soft robot components and bodies, as well as other structuresand devices, although soft robots can be produced using more rigidmaterials if the geometry is appropriate, by using thin, flexibleregions of material (e.g., a robot with a large number of polypropyleneliving hinges). Due to their compliance, elastomers can be more robustunder impact and when subject to stress caused by differential thermalexpansion between metal wire and polymer. Elastomers are soft enough tofacilitate wire anchoring with minimal heating as will be describedhereinafter, and also allow electrical components to be integrated intoa device by pushing leads into regions of elastomer-based ECPC.Moreover, like all thermoplastics, they are recyclable. In the cases orlocations where elastomers are too flexible or weak, strength andstiffness can be increased by incorporating reinforcing filaments/wires(e.g., Kevlar®, carbon fiber, glass) in the polymer matrix, or byintegrating a strong and/or rigid material into the process. In someembodiment variations, a relatively strong, stiff, and preferablysoluble support material—which may be similar in composition tomaterials commonly used for soluble supports in FDM (e.g., Lombardi etal. 2002; Priedeman, Jr. et al. 2004; Stratasys E20 Elastomer Support (athermoplastic copolyester))—deposited along with the matrix material toprovide support of the object during fabrication, may also be depositedand completely or substantially surrounded by matrix material (e.g.,elastomer) such that it cannot be fully dissolved during the cleaningprocess used to remove support material that is exposed. Suchencapsulated support material can thereby strengthen and stiffen thestructural material, especially if it's an elastomer. Conversely, air orliquid-filled voids of various sizes and shapes can be introduced toreduce stiffness. If voids are interconnected through narrow air orliquid passages, then void volume and passage area can be specified soas to control the damping behavior of the structure as it flexes. Insome embodiment variations, integrated filaments and relatively rigidmaterial can be used to form structures that prevent excessive movement(e.g., bending, radial expansion, over-inflation) or to control thedirection of movement, much like ligaments in animal bodies. Forexample, a well-attached filament initially having a serpentine shapewill limit movement when placed in tension once it has become straight.

A FEAM printhead can include additional functionality compared to astandard FDM printhead, for example, the ability to: 1) cut wire; 2) insome embodiment variations, clamp wire; 3) switch between polymer andpolymer with wire; 4) in some embodiment variations, switch from polymerwith wire to bare wire; and 5) in some embodiment variations switchbetween extrusion of pure polymer and polymer-based ECPC. In someembodiment variations, ECPC is deposited by a separate printhead orseparate nozzle, which may have different characteristics (e.g., alarger orifice diameter), especially if the ECPC is not based on the(pure polymer) matrix material or is less compatible with it. In someembodiment variations, ECPC is delivered coaxially with pure polymer. Asshown in FIG. 2, a printhead capable of all of the above comprises anextrusion nozzle with two polymer flow channels and an orifice forextrusion; a slotted capillary having a lumen through which wire is fed;and within the capillary slot, a pair of clamps/cutters. The capillarycan be, for example, a ceramic capillary similar to those used for wirebonding in the semiconductor industry, a steel hypodermic-type tube, apolyimide tube, or other material that can tolerate the elevatedtemperature of the polymer. Not shown for simplicity are elements suchas heated liquefiers located upstream of the flow channels, an optionalnozzle heater (the nozzle may be heated by the same heater as theliquifiers), and in some embodiment variations, two pairs of conductivefeed rollers that advance the wire while heating it resistively andregulating wire tension. In some embodiment variations a key aspect ofthe printhead is the capillary through which the wire is fed. In someembodiment variations the capillary translates and in some embodimentvariations the capillary also rotates about its long axis. The capillarymay provide multiple functions: 1) clamping and cutting wire; 2)adjusting the position of wire within the extrudate in the plane formedby the orifice axis and the extrudate (e.g., a vertical plane); 3)purging the printhead when switching between elastomer and ECPC; 4)increasing control over the wire during winding operations (e.g., forsolenoid cores); and 5) reducing polymer coating thickness (e.g., whenproducing coils). In some embodiments, these functions are divided amongvarious components.

In standard coated wire extrusion, the wire is kept centered withrespect to the extrusion die orifice by a capillary until the insulatingpolymer jacket solidifies, ensuring reasonable concentricity of wire andjacket. In FEAM, the capillary is typically vertical and the “jacketedwire” (i.e., polymer extrudate with wire core) is deposited parallel tothe plane of the layers (see FIGS. 5(a), 5(b), 5(c), and 5(d)):typically horizontal. While molten polymer can easily negotiate thislarge (e.g., 90°) bend, the wire must be also be reoriented and bent. Insome embodiment variations, the wire is gradually bent (to avoid kinks)and guided so as to be reasonably coaxial/concentric in the extrudate(excessive non-concentricity can lead to shorting between adjacent wiresand other problems). In some embodiment variations, soft (e.g.,annealed) wire is selected to facilitate bending in the vertical andhorizontal planes. Concentricity is influenced by such parameters aswire stiffness, printhead speed, and viscosity and solidification rateof the molten polymer. For a given position of the printhead orificeabove the building substrate/previous layer, the vertical concentricityof the wire is controlled, in some embodiment variations, by adjustingthe internal capillary height, wire feed rate, and/or other parameters.However, accurate vertical (or horizontal/in-layer) centering of thewire within the extrudate is not required in some embodiments for theprocess to be useful. In some embodiment variations, this adjustment isdynamic, based on factors (e.g., printhead speed, extrudate geometry,deposition speed) which may change during the fabrication process, andin some embodiment variations closed-loop control of capillary height,capillary horizontal position or angle, or wire feed rate may beemployed in which the vertical and horizontal position of the wirewithin the extrudate (unless the extrudate is no larger horizontallythan the wire itself) is sensed using capacitive, optical, ultrasonic,electromagnetic, thermal, or other means.

Concentricity of the wire within the extrudate in the horizontal (i.e.,layer) plane is influenced by such parameters as wire stiffness,printhead speed, viscosity and solidification rate of the moltenpolymer, polymer strength, capillary rotational angle, and the radius ofcurvature of the extrudate in the horizontal plane. In some embodimentvariations, capillary rotational angle (e.g., in the case ofnon-circular wire) is adjusted to control horizontal concentricity. Insome embodiment variations, this adjustment is dynamic and in someembodiment variations closed-loop control of horizontal concentricitymay be employed in which the horizontal position of the wire within theextrudate is sensed. In some embodiment variations printhead speed isreduced when depositing extrudate along small-radius toolpaths, to allowmore time for the extrudate to solidify and capture the wire.

In FEAM, any given volume element (voxel) within the XYZ extents of thefabricated object can in principle contain one of at least three“homogeneous” materials (not including support material): structuralpolymer, ECPC, and air, as well as combinations of these materials withwire: polymer+wire (e.g., for encapsulated wiring), ECPC+wire (e.g., forconductive junctions), and air+wire (e.g., for actuator armatures,electrodes, etc.). Controlling which of these six or more types isdeposited in each voxel—and transitioning cleanly among them—requires insome embodiments a reliable means of starting/anchoring wire, cuttingwire, depositing “bare” wire with minimal polymer coating, switchingbetween polymer and ECPC, etc. FIG. 3 depicts the six voxel types andthe required transitions, as well as some optional transitions (notrequired for functionality, but which allow for greater design freedom).Some transitions may be impractical and possibly disallowed, such asA-AW (air to air+wire): in some embodiment variations, wire cannot bepulled from the capillary if not anchored in polymer as will bedescribed hereinafter. The inverse transition AW-A is however, practicaland allowable (e.g., by cutting the wire); all such constraints areaccommodated in the software that generates toolpaths.

The functions needed to create the required transitions are 1) cuttingwire, 2) starting wire, 3) producing bare wire, and 4) switching polymertype.

In some embodiment variations, a mechanical cutter near the tip of thecapillary may be used for cutting wire, as is needed, for example, inthe PW-P transition. FIGS. 4(a), 4(b), and 4(c) depict the lower portionof a printhead suitable for wire cutting in some embodiment variations.In FIG. 4(a) a cross-section of the lower portion of the printhead isshown; in FIG. 4(b) a closeup cross-section of the lower portion isshown; and in FIG. 4(c) an isometric view of the printhead capillary,clamp/cutter, and wire is shown. Within a slot in the capillarypreferably perpendicular to the local axis of the deposited extrudateare mounted two small clamps/cutters, e.g., micromachined from hardsteel using a process such as Laser MicroJet® cutting (Synova, Fremont,Calif.), which offers offering 5 μm accuracy and a 25 μm kerf. Eachclamp/cutter includes tabs for contact with the inner taper of theprinthead nozzle, wire clamping shoes through which the wire passes,cutting blades (which in some embodiment variations are staggered toprovide a scissors-like shearing action), flexures, and a mountingsurface. The clamps/cutters may be attached to the capillary by laserwelding using an alignment fixture, crimping, an adhesive, or othermeans. When the capillary is translated axially and forced against theinner taper of the nozzle, the tabs are pushed inwards, bending theflexures and causing the shoes to clamp the wire. If the translationforce is increased, the cutting blades are directly pushed into thewire, cutting it. FIGS. 5(a), 5(b), 5(c), and 5(d) show the PW-Ptransition; the AW-A transition is similar. In FIG. 5(a), polymer isextruded and wire is fed out; in FIG. 5(b) the printhead is stopped andthe capillary is lowered, compressing the clamp/cutter to cut the wire.In FIG. 5(c), the capillary is raised, and in FIG. 5(d), the printheadis moving forward again while extruding polymer. The small length ofwire that may protrude above the layer in FIG. 5(c) is bent into andcaptured by the molten polymer as the nozzle passes over it.

In other embodiment variations, other methods are used to cut, break, orotherwise terminate the wire. For example, wire may be suddenlytensioned to break it, if well anchored in solidified extrudate. Or,wire may be broken through work hardening and fatigue by being twistedeither in one direction (clockwise or counterclockwise), or twistedalternating between clockwise and counterclockwise rotation. Toaccomplish this with non-circular wire passing through a non-circularcapillary hole, the capillary need only be rotated; with circular wire,the capillary may additionally clamp the wire before rotation. Also,wire may be broken through work hardening and fatigue by motions of theentire printhead, not just by capillary rotation. For example, theprinthead may be made to oscillate in the layer plane back and forthseveral times. Wire may be cut using a laser, electron beam, flame, orelectrical discharge, or by rapid stretching or bending,scoring/nicking/partial cutting and stretching (e.g., usingcounter-rotating feed rollers on either side of the scored region),vaporization through resistive heating, or by other mechanical cuttingdevices such as rotating wheels, miniature milling cutters, or blades.It may be preferable to use a method that minimally alters the wireshape (e.g., creating burrs or wider regions) so that it can passthrough the capillary, if the cutting is upstream of the capillary, andso it is not distorted or stressed in its final state, embedded withinthe polymer. However, burrs and distortions can also be corrected byfurther processing of the wire after cutting, such as pulling the wirethrough an orifice in hard material or passing it between two groovedrollers. Mechanical cutting using a very sharp blade (e.g., steel,diamond, glass, silicon, obsidian, sapphire, cubic boron nitride, orsilicon carbide) may be advantageous, as may be a blade which isrotating or vibrating, as in vibratory microtomes. Wire that is cut by ablade may be cut from one side (e.g., against a flat surface/anvil), orfrom two or more sides. Multiple cutting blades, if used, may be alignedor may be offset, the latter causing a shearing effect on the wire.

When a transition such as P-PW is required, a means of starting wire(actively feeding wire when the free end is not already captive insidepolymer) may be used. In some embodiment variations, wire may betransported through the capillary by simply feeding it into thecapillary (e.g., using rollers located between capillary and wiresupply) in a manner that avoids buckling. Preferably the capillaryinside diameter is just slightly greater than the wire outside diameter,and the entrance to the capillary is near the rollers. To facilitateloading of the wire into the capillary, the capillary may be flared atone or two ends, be made from or lined with a low-friction material,vibrated during insertion, or lubricated. Suction may also be used tohelp load the wire.

In other embodiment variations, wire may be fed using a mechanismlocated between capillary and nozzle tip or within the capillary itself.For example, wire may be feed by vibrating the capillary or separatestructures) in contact with it at sonic or ultrasonic frequencies. Ifthe wire surface is suitably textured (e.g., with a saw tooth-likepattern), or if the wire is contacted by a suitably-textured surface(e.g., having a saw tooth-like shape, or having angled bristles), it maybe made to advance in one direction through the nozzle. As an example, asuitable vibratory feeder may consist of two small brushes with angledbristles between which the wire is pressed. The motion imparted to thewire can be more complex than simple vibration (e.g., elliptical) suchthat each cycle the wire is grabbed, advanced slightly, and released topropel the wire: an inchworm-type of motion. The motion of piezoelectricactuators such as the NEXLINE®/NEXACT® Piezo Linear Motors of PhysikInstrumente (Karlsruhe/Palmbach, Germany) may be applicable. Othermethods of feeding wire (and polymer or composite filament) includeminiaturized rolling ring drives (Joachim Uhing GmbH & Co. Flintbek,Germany).

Active feeding, especially in the case of vertical capillaries (i.e.,those parallel to the nozzle axis) may also be used to reduce frictionbetween capillary and wire when the anchored wire is pulled, controlwire height (vertical position) within the extrudate, and reduce thelikelihood that wire will contact the nozzle, which may cause the moltenpolymer extrudate to split into two or more streams.

In some embodiment variations, the wire can be entrained by the flow ofthe polymer and move along with it (possibly at a lower speed) when thewire is made free to move.

In other embodiment variations, the wire is primarily pulled, notpushed, out of the capillary. Pulling the wire requires that it beinitially dispensed a small amount from the capillary and thenwell-anchored in the polymer. Also, the tension in the wire ispreferably well-controlled (e.g., by a slip clutch on the wire spool, orpassing it through rollers equipped with a slip clutch or motor drive).For initial dispensing feed rollers can be used; these may also be usedto assist with wire feeding, thus reduce the strain on the anchored wireand minimizing the risk of wire detachment or polymer tearing. FIGS.6(a), 6(b), 6(c), 6(d), and 6(e) show an approach to wire starting. InFIG. 6(a), the printhead is stopped (or equivalently, the build platformis stopped) and a short length of wire is fed into molten polymer. InFIG. 6(b), the capillary is lowered, clamping the wire, and in FIG.6(c), the printhead is moved relative to layer N (the layer beingformed), impaling layer N−1 with the wire to help anchor it. If thematerial of layer N−1 is relatively soft, impaling it may be relativelyeasy; however, in some embodiment variations the wire is heated orultrasonically vibrated to melt the polymer for purposes of anchoring.

In FIG. 6(d), the capillary is raised, unclamping the wire, and in FIG.6(e), the printhead is moved forward, bending the wire, while polymer isextruded and solidifies around the wire, helping to anchor it. In someembodiment variations, to minimize the risk of pulling out the wireafter impaling the polymer, the capillary is raised a significant amountbefore the printhead is moved so that the wire can more easily bend andwon't be pulled too much horizontally when the printhead moves. Wirefeed distance, impale depth, capillary height, and delay before moving(e.g., waiting until the polymer is fully solidified) may be importantparameters to control the anchoring process. In addition, by anchoringwire in ECPC vs. pure polymer, the higher hardness of the composite dueto the filler can assist with anchoring. In some embodiment variations,a suitably textured wire as described above can be employed to improveanchoring within the polymer and minimize the risk of pull-out. In someembodiment variations, the wire may be stranded or porous to encouragepolymer infiltration and improved anchoring. In some embodimentvariations, the wire surface may incorporate barbs (similar to theQuill™ suture of Angiotech (Vancouver, BC)) or other features which makeinadvertently pulling the wire through the polymer more difficult. Insome embodiment variations, the wire can be looped where needed (e.g.,at regular intervals) so as to better anchor it within the polymer. Insome embodiment variations, the wire in the vicinity of the free end maybe modified to improve anchoring. For example, the process that is usedto cut the wire may also impart a texture on the wire end near the cut.Or the wire may be bent near its tip (e.g., an “L”, “J”, or serpentine,circular, or helical shape) to improve anchoring. In some embodimentvariations, a FAB may be formed at the wire end and the FAB embeddedinside molten polymer that is allowed to solidify. In some embodimentvariations, the printhead may deposit the extrudate/embedded wire in asharply curved (e.g., a “U”) shape after starting the wire, such thatthe curve helps to anchor the wire. In some embodiments, wire will bestarted within ECPC vs. within unfilled matrix as the higher viscosityof ECPC can also help anchor the wire end.

Many of the structures created with FEAM will be created by extrudingwire and polymer together. However, there are situations where bare wireis needed, including creating solenoid cores and capacitor platescontaining the maximum possible volume fraction of metal. Bare wireregions with no residual polymer coating may also be desirable forcreating terminals to connect to separately-fabricated components suchas batteries. In some embodiment variations, polymer coating the wire(including coatings for wires that are pre-coated with insulation, suchas magnet wire) can be removed by laser processing (e.g., CO2, excimer,femtosecond), heating using a heated blade or other device (andoptionally, wicking away melted polymer), burning, creating a FAB (theformation of which will damage the polymer coating), mechanicalstripping (e.g., cutting and pulling, wire brush, abrasive), plasmaetching, wiping the wire (while the polymer is still molten), etc. Tothe extent that the wire is heated or textured to increase adhesion ofthe polymer to it, this can be eliminated in areas that are intended tobe bare.

In some embodiment variations, simply continuing to feed wire whilestopping the feeding of polymer into the printhead liquefier can arrestpolymer flow and yield bare wire, since the wire is surrounded by thecapillary—serving as a sheath—until shortly before it exits the nozzle.In some embodiment variations, to minimize any residual coating on thewire the polymer flow is reversed so as to draw molten material awayfrom the capillary tip. Retracting the polymer filament is commonly donein FDM to minimize the formation of thin strings or to minimize nozzleoozing. Retraction with a suitable velocity profile should extract mostof the polymer from the volume between capillary and nozzle in whichpolymer coating of the wire normally occurs. In some embodimentvariations, the surfaces within the volume to which polymer might adheremay be coated with a low surface energy material such as PTFE orAMC148-18 (Advanced Materials Components Express, State College, Pa.).Since retraction is not instantaneous, the need for bare wire ispreferably anticipated by the FEAM apparatus control software: theprinthead can be stopped or slowed, or retraction initiated beforereaching the bare wire region.

A major advantage of using ECPC is that localized delivery of thecomposite material can be directly integrated into the manufacturingprocess. In some embodiment variations, this can be done by designingthe print head nozzle with two flow channels: one for deliveringpolymer, and one for delivering ECPC, as shown in FIGS. 7(a) and 7(b),while in other embodiment variations, this can be done using separateprintheads and/or nozzles. This allows formation of conductive regions(ECPC surrounding wire, or “CW”) “on the fly” as material is deposited.However, in some embodiments, ECPC or other conductive materials may bedeposited through a separate operation, before or after dielectricmatrix material and wire are deposited (in the former case, the wirebecomes embedded into already-deposited conductive material). Any two CWregions adjacent in the same layer and at least partially overlappingcan form an intra-layer junction (FIG. 8(a)). Separate volumes ofconductive material may in some embodiments be deposited on each wire,while in other embodiments a junction between two or more wires may beproduced by depositing a single volume of conductive material theencompasses the wires. In some embodiments, wires may overlap (e.g.,cross) within the same layer, and may therefore spontaneously form ajunction, but even in such embodiments, the resistance and reliabilityof the junction may in some embodiment variations be improved byencapsulating the wires in conductive material.

Any two vertically adjacent, at least partially-overlapping regions ofconductive material can form an inter-layer junction (FIG. 8(b)),whether there is wire on the two adjacent layers or not (e.g., ECPC“vias” may span multiple layers to connect wires separated by multiplelayers). Direct contact of the wires in these junctions is not required.Junctions can incorporate more than two wires as shown, and in the caseof inter-layer junctions, can span more than two adjacent layers,forming vertically-conductive vias.

Preferably the conductivity of the ECPC is relatively isotropic andhomogeneous throughout the CW region, such that there is a continuouspath of relatively low resistance from wire to wire; for adjacentjunction voxels, this requires low resistance from the location withinthe junction in contact with the wire, to the surface of the ECPC voxelin contact with the other ECPC voxel. In some embodiment variations, amagnetic field can be used to modify ECPC conductivity in favorable waysif the metal filler is magnetic (e.g., Ni). Polymer and ECPC materialare in some embodiment variations delivered to the printhead asfilaments, while in other embodiment variations, they may be deliveredin other forms, such as pellets or powders. Since relatively little ECPCmaterial is needed when ECPC is confined to junctions, and ECPC filamentdue to its high filler content may be challenging to wind on a spool,relatively straight (i.e., large radius of curvature) and in someembodiment variations, larger diameter (e.g., 3 mm) replaceable lengthsof ECPC filament may be used to supply the printhead.

Each of the dispensing channels shown in FIGS. 7(a) and 7(b) isdownstream of a liquefier (not shown) into which filaments are fed byrollers. In FIG. 7(a), the printhead is operating normally, extrudingpolymer. In FIG. 7(b), the capillary has been lowered as much aspossible (without causing the wire to be nicked/cut by the cuttingblade) in preparation for extruding ECPC (the PW-CW transition). Sinceboth liquefiers are “plugged” upstream by solid filament acting as apiston (as in conventional FDM), lowering the capillary purges most ofthe polymer from the nozzle. In some embodiment variations, thecapillary may be designed with a channel that opens up to either thepure polymer or ECPC channel, such that it serves as a rotary valve:rotating the capillary allows either one material or the other to flowthrough the nozzle. The capillary is then raised and the ECPC filamentadvanced to extrude material. The CW-PW transition follows a similarsequence. In some embodiment variations in with ECPC has limited thermalstability, elements of the printhead (e.g., the liquefier) associatedwith melting ECPC and keeping it at deposition temperature are cooledwhen no ECPC is needed soon, to prolong ECPC lifetime.

There may be some uncontrolled mixing of polymer with ECPC andvice-versa in the proposed configuration. In some embodiment variations,by exploiting the “quantized” nature of percolation in ECPCs, reasonablyabrupt differences in conductivity between adjacent regions of anextrudate (“voxels”) that are intended to be dielectric, and those meantto be conductive, are obtained. In some embodiment variations, theparticulate filler concentration is set higher than the percolationthreshold so that minor dilution by unfilled polymer doesn't lowerconcentration below the threshold; yet the concentration is set lowenough that material in dielectric voxels contaminated with lowconcentrations of particulate is not rendered conductive. In someembodiment variations, long (e.g., 1-2 mm or greater) junctions areprovided, such that all “conductive” voxels within a junction need notbe fully conductive to yield a low junction resistance overall. In someembodiment variations, the conductivity of the ECPC is monitored in-situto ensure that a good junction can be formed. This can be performed byincorporating electrodes into the printhead (e.g., within the nozzle) tomeasure the conductivity before extruding ECPC, or can be performed onthe extruded material. Conductivity measurements can be used to optimizefilament and machine parameters, and junctions with inadequateconductivity can be made longer/larger, or additional junctionsprovided, to compensate.

In some embodiment variations, all or much of the length of a wire maybe embedded in ECPC, which can further reduce electrical resistance,provide for a large number of junctions, etc. In some embodimentvariations, design rules used in the layout of a printed structure canavoid locating CW-PW transitions in regions of tightly-spaced conductors(e.g., a coil) to allow for minor conductivity in PW voxels due tointer-contamination of ECPC and polymer.

In some embodiments, ECPC need not be delivered “in-line” along with thedielectric material such that the printhead must switch between the twomaterials and the composition of the extrudate changes dynamically.Rather, the dielectric material and ECPC can be applied through separateoperations. For example, dielectric material may be applied first,leaving a trench one or more layers deep within which at least one barewire is exposed; this is then filled in by deposited ECPC. Such trenchescan be filled by methods differing from FDM extrusion, and may involvemeans for removing excess material such as wiping with a doctorblade/squeegee. Alternatively, for a given layer, wire/ECPC regions maybe formed first and dielectric regions formed afterwards. The trenchapproach allows multiple wires on the same layer or different layers (ifthe trench spans multiple layers) to share the same region of ECPC,which can reduce resistance. In some embodiment variations, trenches maybe formed by placing objects with suitable shape (e.g., a disk orrectangle large enough to form a junction) and depositing materialaround them, then removing the object.

In some embodiment variations square wire (e.g., Fort Wayne Metals, FortWayne, Ind.) is used in FEAM for building “solid” metal volumes. In suchembodiments, the capillary tip has a square orifice (e.g., produced bywire EDM, or by machining the tip in separate halves) and the capillaryrotates during extrusion such that two opposing sides of the wire remaintangential to the platform velocity, forcing the wire to bend in thecorrect plane and preventing wire bulging and/or layer delamination. Insome embodiment variations, the capillary tip is located far enough fromthe nozzle orifice that any twisting in the wire which occurs isdistributed over a significant length. To minimize buildup of torsion inthe wire when following curved paths, in some embodiment variations thewire spool is rotated in the same direction as the capillary (e.g.,synchronously). In some embodiment variations, the buildup of torsion inthe wire is minimized by alternating the deposition direction ofextrudates comprising a layer between a clockwise and counterclockwisedirection. This may be calculated and incorporated into the toolpathplanning, or the torsion sensed and the deposition direction reversedwhen needed. In some embodiment variations, torsion buildup is minimizedby cutting the wire more frequently than otherwise needed, andre-starting it; the wires connect through ECPC junctions as usual. Inthe extreme, cut pieces of wire can be used in FEAM, so that wire is notprovided on a spool but in relatively short pieces. In some embodimentvariations, torsion buildup can be counteracted by intentionallytwisting the wire (e.g., by spinning the capillary) enough to createplastic deformation (e.g., periodic twisted regions along the wire).

An apparatus for FEAM may be configured in some embodiment variations asin FIG. 9. The printhead capillary in some embodiments may be arrangedto pass through a hollow rotation motor. A build platform is providedwith three axes of motion using stages and motor (in other embodimentvariations, the printhead may instead be provided with one or more ofthese axes). A spool provides polymer filament to a printhead, advancingit, for example, using feed rollers. In some embodiments, the filamentis cooled to prevent softening before reaching the printhead liquifier.Cooling can be provided by blowing continuous or pulsed gas onto thefilament, by using cooled feed rollers, etc. ECPC filament is also fedinto the printhead, e.g., using feed rollers (not shown), as is wire,which may be fed using two pairs of rollers, such that the wire isheated resistively (to enhance wire coating by the polymer) by passingcurrent from one pair to the other. To improve traction and electricalcontact, the wire may be wrapped at least once around one roller of eachpair. Inductive or other means of heating the wire may also be used, ascan heating the rollers, heating the capillary (e.g., if external to thenozzle) by contact with a heating element (e.g., wrapping it withinsulated nickel-chromium wire), infrared heating, flame heating,inductive heating, and laser heating, for example. The entire apparatusis preferably enclosed within a temperature controlled environment;alternatively or in addition, the build platform/substrate may beheated. Fabrication parameters (e.g., nozzle/platform gap, toolpathcurvature, and platform speed) may be varied to optimize extrudatewidth, height, uniformity, surface quality, defects, and residual stressdue to shrinkage.

In FDM, the printhead typically moves in X/Y and the part moves in Z. Itmay be desirable to use the standard FDM approach also for FEAM, sincemoving the part or device quickly in X/Y can cause movement andvibration of the previously-deposited material, especially if it iselastomeric, leading to misalignment of layers. Certainly, use of rigidsupport material (temporary or encapsulated) can mitigate this. However,there can be benefits to keeping the printhead fixed in X/Y and movingthe part, since the printhead and its feedstock are different and morecomplex. To compensate for potential misalignment due to rapid partmovement, to facilitate the use of printheads which are relativelymassive and difficult to accelerate, etc., the printhead (or just thenozzle) can be moved by small distances at relatively high speed only soas to “track” the undesired movement of the previously-deposited layer,much as a CD (compact disc) or DVD read head is servoed to track theposition of the disc data track as the disc spins. Computer vision canbe used to identify fiducial marks on previous layers (e.g., internal tothe final object surfaces, or in support material), or the edges ofprevious layers, to provide the requirement positioning data. For thispurpose a camera can be incorporated into the printhead just ahead ofthe nozzle. Alternatively, a very lightweight motion stage can be usedto rapidly position a lightweight extruder or nozzle, or the tip of aheated, flexible tube (e.g., double walled vacuum tubing such as Insulon(Concept Group, West Berlin, N.J.), according to part geometry (e.g.,driven by G-code data), while the additional, heavier hardware requiredfor extrusion is kept nearby, moved by its own motion stage so as tomaintain a not-to-exceed distance from the lightweight stage. The motionof the “heavy” stage does not need to be exact, so long as the maximumdistance between stages is not exceeded; thus, the heavy stage can avoidthe need for high accelerations of which it may not be capable, or whichit may not be able to perform accurately.

FEAM generally requires software to generate suitable toolpaths for theprinthead and to control the apparatus during fabrication. Suchtoolpaths may be generated by processing one or more files defining thegeometry and the functionality of the object to be fabricated. In someembodiments, multiple files may be processed, for example, three .STLfiles (commonly used in additive manufacturing), each defining thelocation of one material (matrix material, filament, conductive matrixmaterial/ECPC). Software generating toolpaths (e.g., after the designprocess, or during it) may in some embodiments preferentially (e.g., asa first step) route extrudates which include embedded filament alonguser-designated or automatically distance-optimized paths on a layer, oralong paths which meet other requirements of the process (such asproviding for intra- and inter-layer junctions or avoiding sharp bendsin the wire). Extrudates needed to form the layer which do not includefilament are also routed, but at a lower priority (e.g., as a laterstep) and in some embodiments, in a secondary process. In someembodiments, toolpaths can be generated such that the number oftransitions between one voxel type and another are minimized, especiallythose transitions which take some time or have the potential tointroduce defects. In some embodiments, the spacing between extrudatescontaining wire and/or ECPC may be arranged so that such extrudates areplaced adjacent to one another (on the same or different layers) aslittle as possible, to reduce the risk of shorts.

FEAM can be used to make and integrate into co-fabricated devices—eithersingly or in a distributed fashion—a wide variety of electromagnetic andelectrostatic actuators and sensors. Electromagnetic actuators that canbe fabricated include solenoids (linear and rotary), voice coils, motors(e.g., axial and transverse flux motors in which the axes of coils androtation are parallel and thus easier to fabricate), and novelconfigurations (e.g., using the attractive or repulsive force betweenadjacent current-carrying wires). Electrostatic actuators include “combdrive” and parallel-plate electrostatic actuators. Electromagneticsensors that can be produced include linear variable differentialtransformers (LVDTs), variable-reluctance sensors, and fluxgate sensors.Electrostatic sensors that can be made include capacitive sensors suchas those using surface or projected capacitance.

Among the devices that can be made using FEAM are DC plunger-typesolenoid actuators. Such actuators are in some embodiment variationsreadily distributed through a robot limb or body and connected bywiring. A typical plunger solenoid actuator (FIG. 10) has a coil wrappedaround a solid or laminated ferromagnetic armature (plunger). Whencurrent flows in the coil, the magnetic field produced in the coreattracts the plunger with a force roughly proportional to the square ofthe coil current [Brauer, 2006]. As the plunger moves inward, an elementsuch as a spring is deformed; when current stops this returns theplunger to its original position. A ferromagnetic stator surrounding thecoil strengthens the flux and improves performance. In some embodimentvariations, solenoids may be cascaded in series end-to-end (i.e., theplunger of solenoid N connected to the body of solenoid N+1, etc.) toincrease displacement, or arranged in parallel to increase force, or ina combination of series and parallel arrangements.

Solenoid actuators may be made using FEAM in several ways. In someembodiment variations, a trench is provided that spans multiple layers,and a coil is continuously wound within the trench using PW voxels, muchlike a standard coil. In other embodiment variations, as shown in FIG.11(a), the coil is made from stacked spiral planar coils: coils arewound clockwise (as shown, or counterclockwise) and joined verticallyboth at the inside and the outside of the coil stack, such that all areelectrically connected in parallel. Such an arrangement reduces overallcoil resistance. In still other embodiment variations, as shown in FIG.11(b), the coil is made from stacked pairs of spiral planar coils: onecoil of each pair is wound clockwise from outside to inside, while theother is wound counterclockwise from outside to inside. The inside endsof both of these are then wired in series, such that current flowsclockwise (or counterclockwise) through both of the coils in the pair.Such an arrangement also reduces overall coil resistance, and suchpaired coils may be continuously wound (i.e., both coils wound withoutinterrupting the wire) or wound separately and joined; if the former,then in some embodiment variations each coil of the pair may be onlyhalf the typical layer thickness, with the pair as thick as the typicallayer. In this configuration both connections are on the outside of thecoil stack. In some embodiment variations, the pattern shown in FIG.11(b) is extended beyond just one pair of coils made using continuouswire, to a large number of coils made using continuous wire, in which onalternating layers, spirals are formed either from the outside to theinside, or from the inside to the outside. In some embodimentvariations, such as to allow closer spacing of coil turns and increasethe number of turns in the coil, the capillary is lowered partially toreduce the thickness of the polymer coating the wire. The gauge of thewire used for the coil can be selected based on considerations ofcurrent handling requirements, weight (since metal is far denser thanpolymer), and suitability for the FEAM process.

In some embodiment variations to improve the force/currentcharacteristic of the actuator the plunger and stator have a largerelative magnetic permeability, and may be made from stacked,spirally-wound bare wire such as nickel (Ni μ_(r)=110-600) or Ni-basedECPC.

In some embodiments, to improve the force/current characteristics of theactuator, e.g., the plunger and stator, materials are chosen having alarge relative magnetic permeability. For example, cores, armatures,plungers, and the like may be made from nickel (nickel μr=110-600) wire,or nickel-, iron, or Permalloy-based ECPC or other filled polymer (notnecessarily electrically conductive), e.g., deposited into a cavity.FIG. 12 depicts a stacked, spirally-wound bare nickel wire plunger, inwhich wire is wound in a spiral path on each “layer” (not necessarilythe same thickness of the device layers). In some embodiment variations,the two ends of the wire on each layer can be anchored in polymer. Insome embodiments, elements such as plungers may be wound in a moreconventional 3-D fashion, using a helical trajectory of the capillary towind wire around a central “spool” of polymer, filled polymer, insertedobject, etc., in a single “layer” of wire, or in multiple “layers”, witheach layer increasing the element diameter. To facilitate windingelements made from bare wire and in some cases, small radii such asthese, the capillary may be lowered within the printhead (or loweredoutside the printhead, if the capillary is external) to better controlthe wire position. Square or rectangular wire vs. round wire is used insome embodiment variations as it can be wrapped to form dense solenoidcores, stators, and capacitor plates; it's also easier to clamp and haveits position sensed within the extrudate (e.g., capacitively,ultrasonically, magnetically, or optically) so that it can be adjustedstatically or dynamically (e.g., by moving the capillary). In someembodiment variations, the plunger is supported by a flexible (e.g.,elastomer) diaphragm or bellows, allowing axial motion and optionally,providing a return force.

Permanent magnets and permanent magnetic materials may be incorporatedinto devices and structures produced using FEAM. For example, thelayer-by-layer building process may be interrupted so that a void ortrench in deposited material can be filled with a mixture of binder(e.g., epoxy) and NdFeB particles and the FEAM process then continued.After solidification (e.g., room temperature or oven curing,solidification from a molten state, UV curing) and magnetization, thematerial forms a permanent magnet: solidification can be achieved beforeproceeding with the FEAM process, or after the entire device is built.Alternatively, a composite of polymer and a magnetic powder can beformed, analogous to ECPC, and then deposited directly through asuitable nozzle (e.g., the FEAM printhead could deposit pure polymer,ECPC, and magnetic polymer). Alternatively, pre-formed magnets can beincorporated into a device made by FEAM by interrupting the process andinserting the magnet into a suitable trench or opening, then continuingthe process.

Capacitance-based actuators may be made using FEAM. For example,dielectric elastomer actuators (DEAs)—a subgroup of electroactivepolymers (EAPs)—change their shape when subjected to an electric field,and typically comprise a layer of elastomer sandwiched between twocompliant electrodes. Due to the small displacements normally produced,these may be stacked to create dielectric elastomer stack actuators(DESA). Compliant electrodes may be in the form of wire (e.g.,serpentine or coiled, preferably without polymer coating), ECPC, orboth. A filled may be incorporated into the elastomer to increase itsrelative permittivity, thus increasing the force per unit area of theactuator (i.e., the Maxwell stress). FEAM enables DEAs and DESAs withcomplex, non-planar shapes not achievable with conventional methods offabrication. DEAs and DESAs may be further co-fabricated with otherelements to create valves, pumps, and other useful devices; however,such devices can also be actuated by FEAM-fabricated electromagnetic,shape memory, piezoelectric, thermal, or other types of actuators.

In other embodiments, FEAM may be applied to making structures frommaterials other than polymers. For example, FDM has been used tofabricate “green” ceramic parts (made from ceramic particles and apolymer binder), which are fired at high temperature after fabricationto form a ceramic of the desired properties. Some clays, ceramics, andceramic-like materials do not require high-temperature firing (e.g.,Rescor™ castable ceramics of Cotronics (Brooklyn, N.Y.)), while othersmay. Using wire (e.g., tungsten, platinum) that is sufficientlyrefractory given the processing temperature of the ceramic, FEAM can beused to make ceramic products with embedded wiring such as customheaters of complex shape, sensors for high-temperature environments,chemical processing devices, medical implants with built-in straingauges and other elements, passive components (e.g., capacitors,inductors, and antennas), etc. In some embodiments, concrete, plaster ofParis, and similar materials may be used in a FEAM process (possiblywith viscosity modifiers to prevent slumping of the extruded material).The resulting parts are similar in some respects to low-temperature orhigh-temperature co-fired (LTCC or HTCC) ceramic parts, but offer farmore complex 3-D geometry and easier, more automated fabrication. Insuch a case, ECPC may be replaced by a conductive material of the kindnormally used for LTCC/HTCC metallization, such as a conductive pastecontaining Ag or Cu, and the wires used for interconnections can be of arefractory material such as tungsten. The ceramic can be a greenceramic-polymer composite which ultimately is fired to create the finalobject. FEAM may be used with molten glass in lieu of molten filament,or glass frit mixed with a binder, to make glass structures withembedding filaments such as conductive wires.

In other variations, bare die or packaged ICs (e.g., microprocessors,signal processors), optoelectronic components (e.g., camera chips,LEDs), MEMS sensors, magnets, piezoelectric crystals, and hardwarecomponents such as bearings can be integrated into FEAM-producedcomponents, for example, by using integrated pick-and-place assemblyhardware to position parts into a structure while it's being fabricated.Connections to pads on semiconductor die can be made by wire bondingbetween pad and FEAM wiring using standard wire bonding techniques(e.g., using the capillary as a wire bonding tool). Or, if the pad pitchmatches the minimum FEAM line width, by direct connection of pad to wireusing conductive polymer (e.g., ECPC), much like flip chip assemblyperformed with conductive adhesives. Solder, especially if lowtemperature, may also be used.

Other variations can include multiple wires co-deposited simultaneouslywithin a single extrudate. FEAM can also be expanded to includecomposites with magnetic filler materials (e.g., NdFeB powder), forminga “permanent magnet polymer composite” (PMPC). “Active” wire materials(such as shape memory alloy wire or contractile nanotube yarn [Lima etal., 2012]) may be substituted for ordinary wire in the printhead,offering more actuator options.

The basic approach of FEAM can be broadly expanded to address a widevariety of technical needs. For example, instead of or in addition toembedding conductive wires, in some embodiment variations fluid conduits(tubes), reinforcing filaments, filaments which produce a change invisual appearance, or optical fibers could be embedded. Likewise,relatively hard materials such as ABS may be used in lieu of, or incombination with, elastomeric materials, and fillers (which may or maynot also provide desirable electrical, magnetic, or optical properties)may be incorporated to modify mechanical properties of the polymer. Insome embodiments, incorporation of relatively low-melting pointmaterials (e.g., polylactic acid, low-melting point metal alloys) can beused to alter mechanical properties such as stiffness or elastic modulusdynamically, based on controlled solidification or melting of thematerial. Moreover, r polymers with tailored optical properties may beused, facilitating direct fabrication of microfluidic devices withintegrated optical components for optical sample analysis. Shape memorypolymers—which change shape or mechanical properties, and if pre-loadedcan generate motion when heated—may be incorporated, with heatingprovided in some cases via Joule heating of embedded wires. Soft gels,including those which are bio-derived or biocompatible such ashydrogels, may also be used for FEAM, either in lieu or polymers or incombination with them.

Advanced electromagnetic actuators such as voice coils and rotary motorsand electromagnetic sensors suck as magnetic pickups requiring permanentmagnets and coils can be fabricated through the integration of apermanent magnetic material and in some cases, suitable bearings.Permanent magnetic material may be deposited (e.g., ferrite, alnico, orNdFeB powder such as fine MQFP powders (Magnequench, Science Park II,Singapore) in a polymer matrix) by modifying the FEAM printhead toaccept a third material, or incorporating an additional printhead. Apolymer composites containing such material may be termed a “permanentmagnet polymer composite” (hereinafter “PMPC”). Bearings can be producedby wrapping wire to form circular shafts and sleeves. Alternatively,prefabricated magnets and bearings can simply be inserted into suitablecavities or be secured by material deposited around them. These andother inserts (e.g., balls, integrated circuits) may be provided withflanges, tapers, bevels, undercuts, pores, textures, holes, or othermeans of improving anchoring in the surrounding material.

FEAM-produced components can incorporate pneumatic or hydraulicactuators, as well as channels, reservoirs, and even pumps. Suchactuators need a source of pressurized fluid, offer a large range ofmotion and high power, and can be made MRI-compatible for medicaldevices such as surgical/interventional instruments. For example, acatheter for treating atrial fibrillation could unfold and navigateinside the heart using built-in actuators, deploying an electrode arrayfor mapping and ablating tissue. Better and more natural-appearingprosthetics, such as a FEAM-fabricated human hand, custom-made for anamputee, should become possible. While actuators embedded in such a handmay be far weaker than human forearm muscles, dexterity and touchsensitivity could be enormously improved over current devices. Usingmaterials such as Pt—Ir wire and long-term implantable polymers (e.g.,Bionate® thermoplastic polycarbonate polyurethane (DSM Biomedical,Berkeley, Calif.)), implants such as drug-delivery pumps andneurostimulation devices could be made, complete with coils fortranscutaneous inductive charging and communication. Orthotics fortremor control using magnetorheological dampers could also benefit fromcustom, low-profile, built-in flexible coils: magnetorheological fluidscan be used to provide variable damping by varying viscosity as afunction of applied current.

By surrounding at least one wire with others that surround it (e.g.,oriented substantially parallel to it) to form a shield, low-losscoaxial-type micro/millimeter-wave transmission lines and passives alsobecome possible, allowing for example, a phased-array radar system to bebuilt into the wing of a small unmanned air vehicle. Such a wing couldfurthermore alter its shape using buried actuators to optimizeperformance, or even flap like a bird or insect wing.

By incorporating suitable wires or other filament in a fabricatedstructure, either as long or short pieces, embedded tags which encodedata (e.g., a UPC product code) can be produced, and such tags would behighly resistant to tampering, counterfeiting, and (if the surroundingmaterial is opaque) detection. For example, radiopaque material soembedded in the form of numbers or bar codes would allow identificationof a device using X-rays, while conductive material might be detectedand a code extracted using magnetic fields or radio waves. Since suchtags can easily be non-planar, their “signature” could varysubstantially with orientation of the sensing radiation; while thismight require alignment when sensing, it also permits more data to bestored and allows verification to be performed, further complicatingattempts at counterfeiting the product in which the tag is embedded.Even randomly placed filaments can be incorporated, as they provide aunique 3-D “fingerprint” which can manifest itself differently accordingto observation angle.

Devices made using FEAM can include sound transduction devices (e.g.,headphones, earbuds, microphones, and sonar transducers), activevibration damping devices, and a variety of sensors. For example, inaddition to touch-sensitive robot “skins”, transparent touch screensusing crossed arrays of fine wires to detect touch when wires contactone another, are stretched (altering resistance as in a strain gauge),or change their relative spacing (altering capacitance), or crossedarrays of ECPC extrudates which change resistivity when pressure orbending force is applied, can be readily made, as can pressure-sensingpads (e.g., for breast cancer detection, fitting of insoles).Temperature sensors can be fabricated using ECPC sensing volumes (e.g.,carbon black-filled), thermocouples and thermoelectric devices based onforming a junction between two wires of dissimilar composition, etc. Hotwire anemometers having wires that are resistively—(i.e., Joule) heatedand exposed to a fluid stream while measuring the wire resistance can beincorporated into devices, as can accelerometers using capacitive,variable reluctance, or other sensing modalities. Even gyros based onmeasuring the Coriolis force acting on a vibrating element (e.g.,vibrated electromagnetically) can be monolithically incorporated.

Soft devices with embedded actuators include those that can be used toapply localized vacuum or mechanical stimulation to promote tissuehealing, those incorporated into large pads that avoid pressures whichcan cause bedsores, and those which adapt to the stump of an amputee toprovide a comfortable, snug socket that minimizes tissue damage andrelative motion.

FEAM can be used to create metamaterials incorporating dielectric andconductive elements and metamaterials-based devices such as lenses thatfocus electromagnetic radiation. If the dielectric element is anelastomer, these can be deformed mechanically to tune their operatingwavelengths, change focal length, etc. Ordinary refractive ordiffractive optics which are tunable and adjustable in focal length,aberration correction, etc. and based on deformation or movement of alens or mirror are also possible, such as low-cost adaptive opticalmirrors used to enhance laser propagation through the atmosphere orbetter view astronomical objects.

FEAM can be used to create primary or secondary batteries that are builtinto a fabricated structure. For example, wires made from two differentmaterials (e.g., copper and aluminum, zinc and manganese, lithium cobaltoxide and carbon, Li₄Ti₅O₁₂ and LiFePO₄) can be embedded in thestructure such that at least some portions of the wires are exposedwithin a cavity as electrodes; the cavity can be filled—either duringfabrication or afterwards—with a suitable electrolyte (e.g., liquid,solid, gel or paste). If the electrodes are embedded in an arrangementthat prevents them from contacting one another, no separator may beneeded. In some embodiments, wires made from two different materials maybe simultaneously encapsulated in the same extrudate; the latter may bein the form of a solid or gel electrolyte, or is porous to allowinfiltration with liquid electrolyte.

FEAM's feature size is comparable to that used in microfluidic devices,which perform analysis or synthesis quickly using small amounts ofmaterial. A shortcoming with such devices is the need for pumps; usingFEAM solenoid-actuated peristaltic pumps could be integrated into adisposable device, as well as channels, reservoirs, active and passivevalves, heaters, electrodes, and optical fiber probes. One applicationof microfluidics is in the integration of chromatophores similar tothose used by the cuttlefish and zebrafish into a robot that needscamouflage or a device that simply needs a variable coloring or opacity.Chromatophores can be widely distributed at a robot surface and functionvia pumping—or changing the shape or orientation of—a solid or a volumeof colored and/or opaque liquid [Rossiter et al. 2012]. Optical fiberscan be used in imaging devices among other applications, and can bescanned in a spiral or raster scan by built-in actuators.

Surgical planning and training phantoms or models can be produced usingFEAM. Such devices can include distributed sensors to measure contactpressures and warn the surgeon of excessive or inadvertent contact withdelicate structures. Phantoms can also include actuators so as to modifytheir shape to match patient-specific or dynamic variations inanatomical structure (e.g., as measured using a CT or Mill scan), thusensuring a more accurate representation.

Complex, bespoke wearable electronics including clothing and helmetsthat incorporate non-invasive physiological and biological sensing(e.g., a blood pressure cuff integrated with a shirt, ECG), inertialsensors, cellular and wireless communications, GPS, displays, fluidictemperature regulation, etc., are enabled by FEAM. For example,stretchable devices can be printed with FEAM similar to those producedby lithographic methods [Kim et al., 2011]—though possibly with largerfeatures—by incorporating wires which are laid in serpentine, helical,or other patterns, which allow deformation under load. Stretchableregions can comprise polymer, ECPC, wire, or combinations thereof. Forexample, a stretchable region may include serpentine elements of polymercontaining substantially coaxial (and thus serpentine) wire.

Orthotic and augmentation devices may be produced using FEAM such asexoskeletons that increase natural human load handling, sense jointkinetics and kinematics, stabilize joints, provide better joint form,and train the wearer in desired motions or poses. The Nike+ FuelBand, asmart elastomer wristband that tracks activities like running usingembedded accelerometers, is a first step toward what is possible.Virtual reality and motion capture input devices such as fingerposition-sensing gloves and garments, as well as haptic displays forforce and touch (e.g., vibration-based texture displays, brailledisplays) are also achievable using FEAM. Energy harvesting can beperformed using devices made using FEAM, including garments and shoesthat harvest the energy of the wearer. Electromagnetic, piezoelectric,or other generators can be integrated into the structure of the devicethrough monolithic fabrication.

As shown in FIGS. 13(a), 13(b), and 13(c), in some embodiments, wire isnot deposited along with dielectric or conductive (ECPC) material asdescribed above. Rather, a layer comprising dielectric material and ECPCis formed and wire is embedded into the layer through a separateoperation. Alternatively, in some embodiment variations, two or morewires may be joined to form horizontal (in-layer) or vertical(between-layer) interconnections/junctions by welding, soldering,brazing, ultrasonic or thermosonic bonding, crimping, winding, pressurecontact, or mutual entanglement, among other methods. In some embodimentvariations, both dielectric and ECPC are deposited before embedding thewire, while in other embodiment variations, one material is depositedfirst, followed by wire. This is then followed by depositing the othermaterial. In some embodiment variations, wire is delivered first, andheld in position (e.g., by slightly melting the previous layer,adhesive) and then both materials are deposited over and around thewire. FIG. 13(a) shows a plan view of a layer in which both dielectricand ECPC have already been deposited to form layer N; some ECPC has beendeposited in-line, and some has been deposited by filling a trench. InFIG. 13(b), wire has been added to layer N through an embedding process(e.g., heating such as Joule heating or through use of ultrasonicenergy) to form intra-layer junctions and the first part of aninter-layer junction. To facilitate penetration of the wire deeply intothe material, the heated or ultrasonically-vibrated tool may befurnished with thin protrusions such that the wire is pushed below theupper surface of the material, which then closes around the protrusionsas it they are withdrawn. For example, a rotating wheel with teeth,similar to a pounce wheel, may be used. The path of the wire need notcoincide with the path of extruded material previously deposited on thelayer, but may follow an arbitrary pattern. In the figure, some sectionsof the wire are exposed (forming AW voxels), possibly to interconnectthe structure with external power, etc. In FIG. 13(c), dielectric andECPC have been deposited on layer N+1, along with wire; at this point,the inter-layer junction between layers N and N+1 is completed.

In some embodiment variations, rather than embedding wire by dispensingit in a particular pattern, conductive regions may be formed by laying asheet of conductive material (e.g., solid foil or mesh) over the layerand selectively embedding regions of the material, e.g., using heat.Non-embedded regions can then be removed or made non-conductive such asby brushing, planarizing, or exposing to suitable chemicals.

FIG. 14 depicts a printhead designed such that the capillary can descendconsiderably further than shown in previous figures while feeding outwire. For example, if such a printhead is used with wire that's veryflexible (e.g., annealed thin copper or gold), the wire can bend in asmall radius as it exits the capillary and the height of the capillarytip inside the extrudate can directly regulate the vertical position ofthe wire inside the extrudate. In some embodiments, however, wire may beof a height comparable to the layer thickness and thus no regulationwould be needed. For example, in the figure, the capillary is set to bea distance A above the bottom of layer N+1, where A is less than thethickness of layer N+1. In such a situation where the capillary tip isbeyond/below the tip of the nozzle even a small amount and in theextrudate, the polymer at the capillary tip is no longer under pressure,and thus there is no tendency for polymer to try to rise up through thecapillary. This allows the hole in the capillary to be larger. Withcapillaries whose tips are position higher, within the higher pressurevolume within the nozzle, positive gas pressure can be applied to thecapillary, or an elastomer or ferrofluid seal may be used to mitigatemovement of polymer up the capillary.

In some embodiments, the printhead (or at least its nozzle) is angled asshown in FIG. 15 such that the angle X between the wire and thesubstrate (or previous layer) in the direction of printhead travel isless than 90°, unlike in standard FDM and the previous figures. At sucha reduced angle, the wire or other filament must bend through less than90°, which may be advantageous since the wire may remain within itselastic range (e.g., if metal) or not fracture if made of a brittlematerial such as ceramic, may be easier to keep coaxial with theextrudate in the vertical plane, etc. To allow for this, the printhead(or at least the nozzle) must be dynamically rotated or tilted as theprinthead (or the device) moves such that the tilt vector and theprinthead travel (i.e., velocity) vector, both shown in FIG. 15, areboth substantially within a vertical plane (i.e., the printhead alwaystilts in a direction tangent to its travel), or the fabricated objectmust rotate. The axis shown in the figure may be used as the axis ofrotation if the printhead is rotated; however, other axes may also beused. If the capillary and/or wire spool is rotated as described above,printhead rotation may be incorporated into the same mechanism thatrotates the capillary and/or spool (e.g., so all rotate together). Insome embodiment variations, adjustment of the angle X may be used inlieu of, or in addition to, adjustment of the capillary tip height, tocontrol the vertical concentricity of the wire within the extrudate. Toavoid collisions between the nozzle and previously-deposited material aswill be discussed below, the nozzle can retract vertically, rotate, ortilt to a more standard angle (e.g., X=90°).

In some embodiment variations, the printhead or nozzle may be angled at90° as usual as in FIG. 16, but the capillary is set at an angle lessthan 90°, such that again the wire does not have to bend through a 90°angle. In this case, the capillary (and optionally, the nozzle and theentire printhead) must rotate so that the tilt vector and travel vectorsubstantially share a vertical plane. The axis shown in the figure maybe used as the axis of rotation if the printhead is rotated; however,other axes may also be used. Again, in some embodiment variations,adjustment of the angle X may be used in lieu of, or in addition to,adjustment of the capillary tip height, to control the verticalconcentricity of the wire within the extrudate. In some embodiments,multiple capillaries may be included within a single nozzle, forexample, to deliver multiple strands of wire, or multiple types of wireor other filament. Multiple strands of wire are useful for increasedcurrent handling without significantly degrading flexibility.Conventionally-made multi-strand wire has the strands twisted together,which facilitates manufacturing. In FEAM, the strands can remainseparate—either one strand per extrudate in a set of parallelextrudates, or several per extrudate (e.g., side by side in extrudateswhose width is greater than their height—making possible even greaterflexibility. Multiple strands can be delivered by multiple capillarieswithin a single nozzle, multiple external capillaries, or multi-lumencapillaries.

To allow room for multiple capillaries, they can be oriented at an angleless than 90° as shown in FIG. 16, and oriented around the rotationaxis. As a particular capillary is used, the group of capillaries (orentire nozzle or printhead) is rotated such that the tilt vector of thecapillary in use and the printhead travel vector are substantially in avertical plane. In some embodiment variations, the capillary, nozzle, orprinthead angle is variable. For example, when not depositing wire orother filament, it is at 90° with respect to the plane of the substrateor previous layer, but the angle is decreased when wire is to bedeposited. In some embodiment variations, multiple nozzles or printheadscan be used at multiple angles, depending on whether wire is or is notdeposited.

In some embodiments, wire deposited in solid form is allowed to softenor become molten when the fabricated device is in use. For example, alow melting point metal (e., solder-like material) incorporated into athermoset elastomer like silicone, or a thermoplastic elastomer with arelatively operating temperature (as limited by the glass transitiontemperature or melting point) can be heated (e.g., Joule heating due tocurrent passing through the metal) until it has melted. Such melting canbe desirable in its own right to reduce mechanical stiffness of thedevice, or may be a byproduct of using high currents to produce largeforces, etc. In some embodiments, channels may be provided (e.g., byembedding tubes or leaving unfilled volumes) into which liquid metal isintroduced (e.g., metals that are liquids at room temperature) to serveas conductors; such metal may be used in liquid or solid form. In someembodiments, conductors may be deposited onto a dielectric layer innon-solid form using such methods as aerosol jetting or inkjet printing,with additional layers formed over the deposited conductor. In someembodiment variations, conductive regions such as those incorporatingECPC may be used to form junctions between deposited conductors onmultiple layers.

In some embodiments, the nozzle is not in direct contact with the top ofthe layer being fabricated, as shown in FIG. 17. Rather, polymer andwire are delivered from the nozzle a distance B above the previous layerN, where B is greater than the desired thickness of layer N+1. Byproviding the extra distance, the wire may be curved and re-orientedhorizontally more gradually than when B is equal to the thickness oflayer N+1. This may be of particular value when using large gauge wireable to handle hire currents, or when delivering filament-like materialswhich are too stiff to bend sharply, or may break, kink (e.g., tubing),or otherwise be compromised if bent with too small a radius. The resultis similar to conventional crosshead wire coating, but with theinsulated wire redirected after extrusion.

As shown in FIG. 18, in some embodiments a curved (or angled, orpolygonal) ramp that is thin at its trailing edge may be provided toguide the polymer and wire onto the previous layer, again allowing thewire to curve gradually. In some embodiment variations, the ramp iscoated with or made from a non-stick material such as PTFE. In such aconfiguration, the ramp may be attached to the nozzle and rotated (e.g.,using the same actuator used to rotate the wire and wire spool toprevent torsional wind-up) such that the ramp curvature is maintainedwithin the plane of the nozzle motion (i.e., tangent to the localcurvature of the extrudate in the X/Y (layer) plane). Rotation may beabout axis A, axis B (coincident with the nozzle centerline), or anotheraxis. In some embodiment variations, viscous drag on the ramp alone mayorient it in the desired direction if the ramp is free to turn on alow-friction bearing, etc. If rotation occurs about the nozzlecenterline, the nozzle can be made square in profile, vs. round; thisallows the extrudate to have flatter sides, which can improve surfacefinish on the printed device.

In some embodiments such as that of FIG. 19, the nozzle extension hasramp-like qualities similar to the ramp of FIG. 18, but furthersurrounds the extrudate: enclosing it both on the top and on the sides,and providing a “roof” which acts similar to the nozzle tip in standardFDM, establishing the top surface of the extrudate and helping to pressit against the previous layer to provide good interlayer adhesion (thiseffect can be achieved with the configuration of FIG. 18 using aroof-like plate or ring, not shown). In effect, the nozzle terminates ina tube that is curved horizontally and is preferably, though notnecessarily, truncated at the bottom such that the extrudate and wirecan be deposited onto the previous layer smoothly and without needing todescend over a step. As with the embodiment of FIG. 18, the nozzleextension, and conveniently, the entire nozzle (and possibly more of theprinthead) rotates around axis C, axis D, or another axis so as tomaintain the extension curvature in the plane of the nozzle motion. Inembodiments such as those in FIGS. 18-19, the ramp or tube may occupyenough space that the extrudate cannot be placed easily in closeproximity to extrudate already deposited on a particular layer. In suchcases, two nozzles may be used in some embodiment variations, with pathplanning that first deposits polymer with wire using ramped or extendednozzles, and then deposits polymer without wire using more typicalnozzles.

In some embodiments such as that of FIG. 20, the capillary itselfcomprises an extension which is curved so as to gently guide the wireinto a horizontal orientation, i.e., bend or redirect the wire, andpreferably allow it to exit concentric with the extrudate. As with theembodiments of FIGS. 18-19, the capillary extension rotates around axisE, axis F, or another axis so as to maintain the extension curvature inthe plane of the nozzle motion. If rigid, the capillary extension can bea bent tube (e.g., stainless steel), a microfabricated component (e.g.,made using MICA Freeform (Microfabrica, Van Nuys, Calif.), etc. In someembodiment variations, the extension is a flexible tube (or thecapillary itself is flexible at the tip or everywhere) such as polyimide(Microlumen, Tampa, Fla.) or laser-machined nickel-titanium such that itbends on its own (e.g., to a maximum curvature) when surrounded by fluiddue to viscous drag. When the printhead is not moving, the tip may thenresume a straight configuration which facilitates wire anchoring byimpaling as previously described. In some embodiment variations, thecapillary extension is retractable (e.g., for protection againstdamage); in some embodiment variations it may be a pre-curvednickel-titanium tube that curves when it is pushed beyond a more rigidtube (or the nozzle), and then is forced to be straight when retracted,in the way of certain steerable needles developed for medical procedures[Sears and Dupont, 2006].

In FIGS. 17, 18, 19, and 20 the wire may be cut outside the nozzlerather than within it as discussed above, e.g., using two blades whichconverge horizontally and shear the wire. Once cut, the wire remainingin the nozzle can be retracted back through the extrudate if desired, orleft to extend beyond the nozzle, with the extrudate deposited aroundit. FIG. 21 depicts a wire cutting apparatus different than that ofFIGS. 4(a), 4(b), 4(c), 7(a), and 7(b) that may be used in someembodiments, in which a sharpened cutting tube capable of verticalmotion and located either inside (as shown) or outside the capillary isprovided to cut the wire. As shown in the figure, the capillary may beprovided with an anvil such that by lowering the tube, the wire ispinched between the sharp tube edge and the anvil and is thus cut. Insome embodiment variations, the anvil may be eliminated, especially whenusing harder polymers. In some embodiment variations, the cutting tubeis rotated to enhance its action. In some embodiment variations, thecutting tube, rather than cutting per se, includes notches which engagethe wire and then break it when the cutting tube is rotated, either inone direction or in an oscillatory manner. In some embodimentvariations, the wire (or other fiber) is not cut, but scored or notched,weakening it in one region; such weakening may be also achieved byresistive heating of the wire (e.g., in a region between tworollers/roller pairs), optionally followed by rapid quenching, or bywork hardening. Bending or tensile stress applied to the wire thenbreaks it in the weakened region. In some embodiments (e.g., FIG. 16) inwhich the capillary axis is less than 90° from the horizontal, cuttingthe wire using a vertically-translating blade can be facilitated.

Prior efforts [Elkins, 1997; Stratasys' E20] efforts to use elastomer inFDM were limited to fairly high durometer elastomers in the range of70-80 Shore A. To accommodate softer elastomers (e.g., 5-60 Shore A),other approaches may be used. Assuming that elastomer is provided to theprinthead in filament form, it need be noted that soft elastomers aredifficult to extrude with good dimensional control. A filament varyingin diameter, for example, may not always form a good “piston” sealwithin the liquefier tube, even though when axially compressed they willexpand within the liquefier according to their Poisson's ratio. While agood seal may be achieved, the increased friction may make pushing thefilament through the tube difficult. FIG. 22 depicts a liquefier tubewith a protruding internal sealing ring, preferably of rounded profile,which can indent the soft filament and facilitate sealing, withoutsubstantially increasing friction. In some embodiments, variables infilament diameter may cause variations in the flow rate of polymerthrough the nozzle, which may manifest themselves as variations in thewidth of the extrudate, leading to inaccuracy. To remediate this, theflow rate may be measured and the feed speed adjusted using a real timefeedback loop.

A second issue with soft filaments is that they can buckle when pushed.Therefore in some embodiments, rather than push the soft filament intothe liquefier using rollers or other methods, the filament is pulledinto the liquefier. FIG. 23 depicts a rotating tube which may be locatedat the entrance to the liquefier, or in some embodiment variations, be apart of the liquefier tube (thermally isolated adequately so thatpolymer engaging the projections remains substantially solid). The axisshown in the figure may be used as the axis of rotation if the printheadis rotated; however, other axes may also be used. Again, in someembodiment variations, adjustment of the angle X may be used in lieu of,or in addition to, adjustment of the capillary tip height, to controlthe vertical concentricity of the wire within the extrudate. In someembodiments, elastomeric filament is pushed into a liquifier (e.g., byrollers), and the elastomer is cooled to prevent premature softeningusing gas (e.g., air) jets, refrigerated gas streams, passage through atube through which cool air circulated, liquid (e.g., water) cooling,volatile liquid mist or spray, synthetic jet, contact with cooledrollers, etc.

In some embodiments, rather than providing pure or filled elastomer tothe nozzle in the form of a filament, it may be provided in the form ofpowder, granules, or pellets. For example, material in such a form maydescend from a suitable hopper through a flexible tube that allows theprinthead to move, or may be stored in the printhead itself. In suchembodiments, the material may be pressurized, liquefied, and extrudedthrough the nozzle using a miniaturized screw similar to that found on alarger scale in single screw extruders. In some embodiment variations,the screw delivers material into a small chamber whose volume iscontrolled by a sliding piston (FIG. 23); the piston can slide to adjustflow rate precisely, and can retract to cause polymer retraction fromthe nozzle. In some embodiments, a small gear pump may be used in lieuof, or in addition to, a rotating screw.

In some embodiments, filament is provided in the form of a ribbon andfed into a miniature version of a drum extruder [Rauwendaal, 2001]. Suchan extruder can pull filament into it, avoiding buckling, and with atapered feed region, can also accommodate thickness variation in theribbon.

In some embodiments, unanchored wire can be pulled instead of pushedthrough the capillary. For example, wire can be embossed with teeth orgrooves as part of its manufacturing process, or this can be done enroute to, or inside, the nozzle. Such teeth or grooves can be engaged bya small rotating gear or a reciprocating/vibrating toothed element topull the wire, or such a gear or element can directly push plain wire,especially if soft enough to indent or emboss it slightly. In someembodiment variations, wire can be provided with threads so it can bepulled by rotating a nut. Or, wire can be threaded within the printheadif soft; rotating thread-cutting teeth inside the printhead can pull thewire forward much like filament is pulled in FIG. 23. To preventtorsional wind-up, square wire can be used and passed through a squarehole before threading. The thread need only be at the wire edges; thewire doesn't have to be threaded so deeply that it ends up substantiallycircular).

Since electrical conductivity along the layer stacking/vertical/Z axisnormally provided by ECPCs, the conductivity can be significantly lowerthan in the X/Y plane, where wire provides the primary electrical path.In general, devices might most favorably be oriented for fabrication,and interconnects designed, so as to minimize the use of ECPCs andmaximize the use of wire. In addition, there are several options tomitigate the anisotropy in conductivity. For example, ECPCs made usingelastomer normally increase in conductivity when compressed, which canbe useful in pressure or force sensors, for example. Thus, if completeddevice (e.g., after removal of any support material) is compressedentirely or in selected region along the Z axis, the conductivity alongthat axis will be improved. Another method is to provide lowerconductivity vias along Z. After fabrication, wire can be threaded(e.g., using a needle if not sufficiently stiff) through ECPC regions;the wire can be heated to facilitate penetration through thermoplastic.In some embodiment variations, a channel can be provided to accommodatethe wire, facilitating insertion. In lieu of wire, channels throughvertically-stacked ECPC regions can be provided that can be filled withliquid metal that solidifies (e.g., a solder or other low melting pointalloy) or remains liquid.

FIGS. 24(a), 24(b), 24(c), and 24(d) show a method of enhancinganchoring that may be used in some embodiments. In FIG. 24(a), theprinthead (or the nozzle and capillary) is tilted toward the left. Theaxis shown in the figure may be used as the axis of rotation if theprinthead is rotated; however, other axes may also be used. Again, insome embodiment variations, adjustment of the angle X may be used inlieu of, or in addition to, adjustment of the capillary tip height, tocontrol the vertical concentricity of the wire within the extrudate.

FIG. 25(a) depicts an approach to enhancing interlayer adhesion andreducing the resistance of junctions along the Z axis by creating loopsof wire which protrude upwards from the layer in which they are formed(e.g., layer N as shown) into the space that will be occupied by layerN+1. Such loops can be formed, for example, by movement of the capillaryand/or nozzle, synchronized with forward (X/Y plane) movement of theprinthead. Polymer flowing around the loops when creating layer N+1mechanically interlocks the layer to the loops, just as the loops arewell mechanically interlocked to layer N. Moreover, wire in layer N+1can be in contact or near-contact with the loops, minimizing junctionresistance. In some embodiment variations, the capillary can plunge fromlayer N down into layer N−1 (not shown) so as to embed wire (especiallyif heated ultrasonically or thermally) in the previous layer. Wire isthus delivered in part to layer N−1 while the polymer in that layerre-solidifies in the wake of the capillary.

In FIG. 25(b), the loops are created in the X/Y plane (e.g., by rapidlateral movements of the printhead or just the capillary, causing thewire (with a thin coating of polymer) to deform in the plane), andextend laterally beyond the boundaries of the extrudate. Such loops canassist with increasing mechanical properties within the X/Y plane. Insome embodiment variations, the capillary can be vibrated (e.g.,perpendicular to the local printhead velocity) with a small amplitudewhen required, so that the embedded wire is forced into a serpentine andbecomes better anchored (and the overall structure reinforced), at thecost of increasing wire length, and thus resistance.

If relative rigid support material is used, its selective removal afterthe device has completed building may be enhanced by methods suchbending, squeezing, or twisting the device, which can fracture thesupport with minimal damage to the more flexible elastomer structure. Insome embodiment variations, actuation of embedded actuators (e.g.,flexing wires) can create motions that help to break up and dislodge thesupport material. Moreover, chemical dissolution of the support materialin long, narrow channels or through small holes can be enhanced by fluidpumping motions induced by actuators embedded in the device.

In some embodiments, ECPC is not provided only for junctions, butrather, wire is always delivered to the device surrounded by a matrix,or jacket, of ECPC. This avoids the need to switch between ECPC and purepolymer as often. Moreover, if two nozzles are used—one for pure polymerand one for ECPC and wire—the latter can be specialized and optimized(e.g., rotating, including ramps for gradually curving the wire) forwire and ECPC delivery. A disadvantage of ECPC jacketed wire is thatisolation of two wires requires an air gap or a region of pure,dielectric polymer to be created between the wires, thus increasing thewire pitch considerably. Another concern is the increased stiffness ofECPC vs. pure polymer with ECPCs made using high loadings of powder;this can be mitigated somewhat using nanotube fillers and otherparticulates which achieve percolation at lower volume percent.

In some alternative embodiments, rather than create a polymer-wirecomposite upon exit from the printhead as described above, pre-exitingjacketed wire of the desired outside diameter can be laid down by adeposition head moving in X/Y. If the jacket is a thermoplastic, then itmay be slightly melted (e.g., by IR or nozzle contact) so that itadheres to jacketed wire on the previous and same layer. If not (e.g.,if the jacket is silicone), and adhesive can be applied just prior todeposition, or a heat- or UV-activated adhesive may be incorporated intothe jacket or applied to it.

FIG. 26(a) depicts a novel electromagnetic actuator in the form of adome-like structure supported at its upper edge and comprisingmulti-layer, spirally-wound insulated elastomer wire, produced via FEAM.Preferably, to eliminate ECPC junctions, this structure is fabricated asa continuous tapered helix in 3-D, rather than one layer at a time.Indeed, FEAM may be used to form planar or non-planar layers of materialwith continuous embedded filament, such as a carbon fiber-reinforcedpolymer structure comprising multiple layers, with the direction of thefilaments varying among the layers (e.g., alternating 90° on even andodd layers) to increase strength. In such uses, ECPC may be omittedsince the goal is to produce improved mechanical properties byincorporating of filaments. To create such non-planar layers theprinthead normally translates relative to the structure being fabricatedin three axes simultaneously, not just two as when forming planarstructures. The actual cross-sections of the insulated wire may benarrower or different than those shown in the figure. As shown in FIG.26(a), the bottom of the device is normally at a distance M below theupper edge. However, as shown in FIG. 26(b), when current is passedthrough the wire as indicated by the current direction symbols,neighboring wires attract one another, causing the dome to flatten outsuch that the distance between the bottom and the upper edge is now N,where N<M. This displacement can be used to accomplish a desiredactuation. In some embodiments, the dielectric material of the actuatormay be filled with a magnetically soft powdered material such asferrite, nickel, or iron (coated if needed) to improve performance. Insome embodiments, to increase flexibility, the dome structure may becorrugated somewhat like a bellows, e.g., such that in a cross-sectionalview such as FIGS. 26(a) and 26(b), the walls meander (e.g.,sinusoidally). Capacitance-based actuators based on this design may alsobe created, as can SMA-based actuators relying on contraction of a longwire. In one application, structures such as those in FIGS. 26(a) and26(b) can be placed against a reasonably smooth surface in thepowered-on configuration of FIG. 26(b) and then be transformed to thepowered-off configuration of FIG. 26(a), creating a partial vacuum, andthus serve as controllable suction cups, as is useful in pick and placesystems, climbing robots, and robotic tentacles, etc. In anotherapplication, rapid transitioning between the configurations of FIGS.26(a) and 26(b) while immersed in a liquid can be used in ajellyfish-like manner to propel a robot, for example, to which thestructures are attached.

In general, elastomeric actuators and sensors with embedded wire can bebuilt so that at least a portion of the elastomeric structure contains amagnetically soft powdered material through which the magnetic flux canmore easily flow. Since powder-filled elastomer may be stiffer than pureelastomer, depending on such parameters as powder volume fraction,particle size, and particle shape, the structure may be designed to bemechanically less stiff in regions comprising stiffer material, tomitigate excessive stiffness. In some embodiments, the structure may bedesigned so as to follow the natural lines of force.

In FIG. 27(a), multiple dome-like actuators have been arranged(preferably co-fabricated) in series such that the displacements of eachadd; thus the motion of a shaft relative to a fixed surface to which thebottommost dome is attached can be considerable. In FIG. 27(b), theactuators have been arranged in parallel, such that the force on theshaft is the sum of the individual actuator forces. Combinations ofparallel and serial arrangements may also be used. Filling gaps withcompressible or compliant magnetic material may improve performance.

FIG. 28 shows a balanced tension type of actuator. In the figure, acarriage is held between two tensioned elastomer strips, each of whichhas a serpentine wire embedded within. When current is passed throughone of these strips, mutual repulsion of the wires (since the current inany neighboring pair passes in opposite directions) reduces the tension,causing the carriage to move toward the opposite strip due to thetension in it. In general, by incorporating wire that is not straight(e.g., a serpentine) into an elastomer as in FIG. 28, a stretchablestructure results in which the wire becomes at least somewhat straighterwhen the elastomer is stretched, yet electrical performance ispreserved. The wire in such a structure in some embodiments is printedwhile it is encapsulated by elastomer, and the additional elastomerrequired for a given layer is subsequently printed in the regions notoccupied by wire.

Since ECPC can be visible in regions in which it is incorporated, it maybe desirable to locate junctions away from the visible surfaces ofdevices, so as to not mar their appearance.

Fluid passages may be built in place for various purposes. For example,if located in close proximity to wires used in electromagnetic and shapememory alloy (SMA) actuators, such passages may be used to convey acooling fluid (e.g., allowing higher power to be supplied to a solenoid,or faster response of an SMA actuator), or a heating fluid to increasethe efficiency of an SMA actuator. In some embodiments, hollow wires maybe employed, through which cooling fluid may travel. Pumping of liquidsmay be as a result of one or more localized pumps, or distributedpumping may be employed. For example, wires in close proximity willexhibit mutual attraction or repulsion when supplied with current. Theseforces can be used to slightly deform the geometry of nearby fluidchannels (e.g., located between two wires) so as to achieve a pumpingeffect (e.g., peristaltic pumping). It may be advantageous for suchdevices to use pulsed DC or alternating current in lieu ofunidirectional DC current, to achieve a pumping effect.

In some embodiments, shape control of a device or structure made usingFEAM may be provided, for example, to compensate for creep, inelasticdistortion due to excessive strain, and other sources of distortion.Displacement or force control of actuators used for shape control (or ingeneral) can be implemented by incorporating displacement/positionsensors such as electrostatic or electromagnetic sensors (e.g., LVDTs orvariable reluctance sensors), strain gauges, etc.

FIG. 29 is a cross-sectional elevation view depicting two capillariesthat are external to the nozzle in some embodiments, and which deliveror lay wire into the molten extrudate as the nozzle (or fabricatedobject) moves. External capillaries offer a number of advantages overthose within the nozzle, for which the angle of the axis with respect tothe nozzle axis is more constrained. For example, by allowing the wireto pass through the lumen of the capillary and enter the extrudate withlittle bending, less residual stress is imparted to the wire, which formost wires (e.g., other than superelastic nickel-titanium) may cause itto curl the deposited layer, and thicker and/or more brittle wire andfilament can be accommodated. Moreover, there is less friction betweenthe wire and capillary, facilitating the use of wire feeding and cuttingmechanisms such as FIGS. 32(a), 32(b), 33(a), 33(b), 33(c), 33(d), and33(e), as an alternative to anchoring wire as a means of dispensing it.Since the capillary is not within the nozzle, there is no pressurizedpolymer around it, so no risk of polymer entering the capillary, and noblockage of flow through the nozzle (especially useful for ECPC). Thevertical position of the wire within the extrudate can be easier tocontrol, since a vertical displacement of the capillary translates moredirectly into a vertical displacement of the wire. Also, the horizontalposition of the wire can be controlled more easily using an appropriatetranslation system, without the space constraints of being internal tothe nozzle. Bare wire (e.g., for winding cores or making externalinterconnects is easier to deliver with an external capillary, as it ispossible to avoid any contact between molten polymer and wire (in someembodiments, the polymer flow may be retracted/sucked back into thenozzle, and/or the nozzle may be briefly separated vertically orhorizontally from the capillary to avoid contamination of the wire). Itis easier to implement multiple capillaries with multiple filaments asin FIGS. 45(a) and 45(b), or multiple filaments per capillary (e.g., toincorporate multiple filaments in the extrudate). Finally, rapidmovements of the capillary (e.g., to create shapes such as that of FIG.72) are move easily produced without having to move the capillary insidea viscous polymer. To realize these benefits, however, may require theincorporation of several approaches, as described below.

If the capillary feeds wire asymmetrically from one side of the nozzle,in some embodiments the capillary rotates around the nozzle as it movesaround curves in the layer (X/Y) plane, while in other embodiments thefabricated object rotates with respect to the capillary (e.g., aroundthe nozzle axis, as in FIG. 42). With such capillaries, the wire may beanchored within the object and pulled through the capillaries, or thewire may be fed by advancing it through the capillary, as will bediscussed. In FIG. 29(a), the capillary is straight and the wire bendsin the vertical plane after exiting from the capillary (the bend radiusmay be larger than shown). The vertical position of the capillary, orits angle gamma to the horizontal, may be adjusted to control thevertical position of the wire inside the extrudate for layer N+1.Moreover, the horizontal Y (perpendicular to the figure plane) positionof the wire may be controlled by translating the capillary along the Yaxis or rotating it about the axis of its upper, straight portion.

If the lower edge of the capillary is below the plane defined by thebottom of the nozzle, the capillary can collide withpreviously-deposited material. Thus, the vertical position of thecapillary may be set to be above this plane, as shown, or may bedynamically variable, such that the capillary lifts out of the waytemporarily when a collision might otherwise occur. If wire is cutupstream of the capillary, it may still be pushed through the capillary;however, short cut wire segments would be unsupported between thecapillary and extrudate and cannot be accommodated.

FIG. 29(b) illustrates a cross-sectional elevation view of an externalcapillary comprising a curved tube, the tip of which can be at thecorrect position (in Z and Y) and angle to deliver the wire into thecenter of the extrudate, or to another desired position. Wire isdispensed through the lumen of the capillary which is located andoriented such that the longitudinal axis of the tip (having its lumennearest the nozzle) is at a small angle to the plane of the previouslayer and build substrate. The internal cross-sectional shape of thecapillary can be circular (for round, hexagonal, or octagonal wire, orfor square or rectangular wire in which the twist orientation is notcontrolled), square (for square wire with controlled twist), rectangular(for rectangular wire with controlled twist), etc. The tip can also moreclosely approach the extrudate and even enter it as shown, offset fromthe nozzle centerline by a distance D. X can be zero or a small number,such that the capillary tip is immersed in extrudate; though coated withextruded polymer, the tip can be unclogged by wire entering it, and thecapillary can be heated to melt polymer at the tip and/or heat the wire.However, in some embodiment variations, D is a larger distance such thatthe tip does not touch the polymer. To avoid collisions withpreviously-deposited extrudate, the wire can be retracted or translatedand the capillary translated in X (as needed) and Z, or rotated (e.g.,around the X axis) to move it above the bottom of the nozzle. Thus, forexample, when extruding polymer into a closed, circular, single-layerextrudate starting at 0°, as the nozzle approaches 0° again, the wire(if extended) is retracted, and the capillary is moved above the bottomof the nozzle. While this means that wire cannot be deposited everywherein a closed loop, this is rarely a concern (for situations where it maybe, such as producing conductive loops in metamaterials, ECPC can beused to bridge the gap). For example, when building a layered, verticalaxis coil, wire might be deposited within 300-350° of arc for each turn,before terminating in an ECPC vertical junction and continuing on thenext layer. In the case of a continuous coil as in FIG. 61, noretraction is required. In some embodiment variations, the entirecapillary need not be positioned or angled, but just the most downstreampart of the capillary, if the capillary is at least in part flexible. Insome embodiment variations, collisions can be tolerated if the capillaryis relatively thin and heated so it can penetrate previously-depositedmaterial.

Suitable materials for capillaries and portions of capillaries includestainless steel hypodermic tubing, ceramic tubes, glass micropipettes,and polymer (e.g., polyimide, PTFE) tubes. The upstream end of thecapillary may be flared to facilitate insertion of the filament. Thedownstream tip of capillaries may be radiused (e.g., by micro abrasiveblasting or electrochemical polishing) to minimize friction andpotential damage to the wire. Capillaries may be made from multiplepieces that are bonded or fastened together. Capillaries may be coatedor lined with PTFE (e.g., Thermech Engineering, Anaheim, Calif.), orcoated with AMC148-18, etc.

In some embodiments, wire may not initially be co-deposited withpolymer. Rather, a heated capillary such as that of FIGS. 29(a) and29(b) is immersed through the polymer and moved in X/Y, deliveringfilament as it moves.

FIGS. 30(a), 30(b), and 30(c) depict a cross-sectional elevation view ofan external capillary used in some embodiments and similar to that ofFIG. 29(b), the tip of which can be at the correct position and angle todeliver the wire into the center of the extrudate. Again, due to theasymmetry, rotation of the capillary or fabricated object is needed. Inthis case the capillary comprises a thin walled, curved, elastic tubethat is surrounded partially by a stiff guide tube. The elastic tube maybe made from superelastic nickel-titanium, stainless steel, or apolymer, for example. If the tube is curved in the X/Y plane tonaturally have a shape such as that shown in FIG. 30(c), when withdrawninto the guide tube it is forced to straighten out. While thearrangement of FIG. 29(b) may require two axes of motion to bring thecapillary above the bottom of the nozzle, a single-axis retraction ofthe capillary into the guide tube in FIGS. 30(a), 30(b), and 30(c)accomplishes this. The guide tube can be translated and/or rotated, andthe capillary can be extended or retracted by various amounts, to adjustthe position and orientation of the tip of the capillary. For example,the distance D between the nozzle axis and the tip of the capillary canbe adjusted (e.g., to minimize potential contamination of the capillarydownstream end/tip, or wire that is intended to be “bare”. If distance Dis small and the tip is in contact with molten polymer, the capillarycan be heated to prevent or eliminate clogging by polymer; such heatingcan also pre-heat the wire, which can improve coating with polymer andadhesion. In some embodiments, distance D is adjusted dynamically. Toavoid collisions with previously-deposited extrudate, the wire andcapillary can both be retracted to move them above the bottom of thenozzle. In some embodiments, the entire downstream/distal end of thecapillary is not retracted; rather, the tip is simply deflected upwardsso that it no longer protrudes below the bottom of the nozzle. Also, theoutside dimensions of the portion of the capillary below the nozzleshould be smaller than the extrudate width horizontally, so that wiredelivery/polymer extrusion can occur immediately to the side ofalready-deposited extrudate. It should also be smaller than the layerthickness vertically, so that the wire can be centered vertically ifneeded with respect to the layer thickness. In some cases the capillarymay need to be placed lower than the center of the layer thickness,e.g., to compensate for hydroplaning of the wire on the molten fluid, orhigher than the center, e.g., to compensate for depression of the wiredue to impingement of the polymer flow. To deliver bare wire (e.g., forwinding a capacitor plate or electromagnetic actuator core), wire can beretracted (if needed) into the capillary and polymer retracted from thenozzle (e.g., by reversing the feed rollers). Once the region underneaththe nozzle is free from polymer, the wire can be re-extended.

In some embodiments, the wire height (for square wire) or diameter maybe substantially equal to the layer thickness, such that the nozzlevirtually rides on the wire surface, the wire is flush with the bottomof the layer, and polymer is on either side of the wire, but notelsewhere. In such a case, the capillary tip may be at a larger X valuethan in FIGS. 30 (a), 30(b), and 30(c) so that it doesn't interfere withthe nozzle.

In some embodiment variations, the capillaries of FIGS. 29(a), 29(b), 30(a), 30(b), and 30(c) need not guide the wire very far toward the pointof entry of the wire into the extrudate, but rather, may “aim” the wireat the desired entry point, such that the wire spans the gap betweencapillary tip and extrudate without further support. The capillary aimwill depend on whether the wire issues from the capillary in a straightor curved form once its internal stress In some embodiments, feeding offilaments may be performed using apparatus similar to that shown in thecross sectional view of FIG. 31. To minimize the possibility that wire(especially if its stiffness or yield strength is low) will buckle, thewire is surrounded as much as possible by the capillary, especiallydownstream (in the direction of motion) of the rollers. A singlecapillary with cutouts similar to those shown allows contact between thecounter-rotating rollers and the wire. The rollers can be metal, polymer(e.g., elastomer), ceramic, or other material. In some embodimentvariations, both of the rollers are driven by a motor, while in otherembodiment variations, one roller is driven and one rotates passively.Motion of the rollers in the direction shown displaces the wire in thedownstream direction shown, i.e., extends it from the capillary,typically at the same tangential speed as the printhead nozzle moves(though this may vary if the intent is to preload the wire in tension,create more complex wire shapes as in FIG. 72, etc.). Reversing theroller direction reverses the wire direction, i.e., retracts the wire.At least one of the rollers may also serve as one electrode, along withat least one (driven or passive) upstream roller (or brush, etc.) toprovide Joule heating of the wire by the passage of current from theroller to the upstream roller.

In FIGS. 32(a) and 32(b), apparatus applicable in some embodiments(e.g., those using an external capillary) for feeding filament is shownin isometric view. As shown in the closeup view of FIG. 32(b), a closeupview of FIG. 32(a), two rollers are provided, as well as twocapillaries: one upstream (to guide the filament) and one downstream(i.e., toward the nozzle) of the rollers, separated by a small distance(particularly small between the downstream capillary and rollers) toallow access of the rollers to the filament. A single capillary shapedlike that of FIGS. 32(a) and 32(b) which allows roller contact with thefilament can also be used. In FIGS. 32(a) and 32(b), one roller isdriven by contact with an elastomeric friction roller turned by a motor,while the other turns passively. The speed of the motor is preferablyvery well controlled and adjustable with high resolution, so as toachieve the desired wire feed rate. For example, the wire may be fed atprecisely the same speed that the nozzle traverses the previous layer orbuild platform; however, other speeds may also be used. The gap betweenthe rollers can be pre-set to firmly grip the filament, or at least oneroller can be spring-loaded. Especially if Joule heating is not used, atleast one of the rollers may be made from or covered with elastomericmaterial. In some embodiments, two rollers are driven at differentspeeds to induce residual stress in the wire and pre-curve it, e.g., sothat it can more easily follow the curved trajectory of the printhead,or conversely, counteract residual stress already in the wire (e.g.,resulting from it being spooled, not straight). In some embodiments, twoother rollers or deflectors are provided downstream of the two rollers,which can translate perpendicular to the wire feed direction, and induceor counteract residual stress in the wire if needed.

In some embodiments, the filament may be fed by a single roller pressingagainst a filament resting on a flat surface, or in a curved,rectangular, or V-shaped groove. Preferably the material the filamentcontacts is a material like PTFE or AMC148-18 with a low coefficient offriction.

In some embodiments, the rollers feeding the filament also provideadditional functions, such as embossing the filament with a texture thatincreases bonding to, and anchoring of, the filament to the polymer(chemical or plasma etching of the wire, or adding a conductive primerto the wire and/or polymer, can also assist with bonding and anchoring).The rollers may also provide a residual stress to the filament that isdesirable in the printed object, or at least partially mitigate aresidual stress that would otherwise remain in the printed object. Forexample, when wire is dispensed from a vertical capillary, it may bebent through approximately 90°, resulting in a residual stress thattends to curl an extrudate containing the wire upwards. Or, when wire isdispensed from a substantially vertical capillary, it may be bent in thehorizontal (layer) plane to conform to the shape of a curved extrudate,again resulting in residual stress. In some embodiments, desirableresidual stress may be imparted to the filament, or counteracted ifalready present (e.g., due to spooling) by feeding the filament betweena relatively large, soft roller and a relatively small, hard roller, theformer tending to plastically deform the wire around the latter.

FIG. 33 shows a view (e.g., a bottom view) of a printhead applicable insome embodiments, comprising filament feeding apparatus and means ofcutting wire. The printhead includes a nozzle for polymer delivery,three capillaries (upstream, center, and downstream), feed rollers, anda cutting blade and anvil located between the center and downstreamcapillaries. In some embodiment variations, the downstream and centercapillaries are combined into a single capillary (e.g., ceramic, such asmade by Morgan Advanced Materials, Fairfield, N.J.) having a slotthrough which the blade can access the wire, cutting it against theinside wall of the capillary; no anvil is then required. To the right ofthe printhead is a supply of wire (e.g., on a spool). In FIG. 33(a),while the printhead moves to the right (or, the fabricated object movesto the left); wire is fed to the left by rotation of the rollers,embedding into the polymer. At this time the blade is retracted. In FIG.33(b), the printhead has paused momentarily (if required) and therollers have briefly stopped turning (if required). The blade is quicklyadvanced to cut the wire against the anvil, and in FIG. 33(c), the bladeis quickly retracted, leaving a cut wire segment within the downstreamcapillary. In practice, the blade motion can be so rapid that neitherthe printhead nor the wire need stop moving. Since the wire is cutupstream of the nozzle, the machine control software must “look ahead”of the current nozzle position to determine the length of wire needed,thus compensating for the distance between the nozzle and the blade. InFIG. 33(d), the wire is again fed by the rollers while the printheadmoves. The cut wire segment is pushed to the left by the motion of theuncut wire, eventually completely exiting the downstream capillary. Insome cases multiple short pieces of wire may be within the downstreamcapillary. In FIG. 33(e), the printhead has advanced further to theright, and the cut wire segment has remained behind, with the uncut wireready to be fed into another region of the object. In some embodiments,wire is tensioned before cutting and in some embodiment variations, thewire is necked down in a region before cutting it in the region, so thatthe incidence of burrs that protrude beyond the wire diameter isminimized. Tensioning can be achieve using an additional set of rollersor a wire brake downstream of the cutting blade, or by pulling on wirethat is well-anchored in the fabricated object using the rollers shown.In some embodiment variations, wire is not only cut, but the end of theupstream portion also deformed so as to better anchor in the polymer;the downstream capillary can be designed to accommodate the deformedwire. In some embodiment variations, the capillaries comprise grooves ina block against which a block of hard material (e.g., ceramic) is fixed;the resulting channel then serves to guide the wire, with the hard blockproviding an anvil. The wire cutting approach of FIGS. 33(a), 33(b),33(c), 33(d), and 33(e) may also be used for wire that is fedsubstantially parallel to the nozzle axis.

FIGS. 34(a) and 34(b) depict apparatus for cutting wire used in someembodiments and having some similarity to that shown in FIG. 21. Thecapillary through which the wire is fed is surrounded by a perforatedsupport tube, and the lower edge of the capillary is sharpened (e.g.,electrochemically). The perforations in the tube allow molten polymer toreach the wire and minimize the flow restriction in the nozzle. When thecapillary is positioned high relative to the support tube (FIG. 34(a)),the latter serves to prevent contact between the wire and the edge ofthe nozzle (which can cause the extruded polymer to split into twostreams). The edge of the support tube also affects the verticalposition of the wire inside the extrudate; thus adjusting its verticalposition can adjust this position. In the configuration shown in FIG.34(a), the wire cannot easily come into contact with the sharp edge ofthe capillary. When the capillary is positioned low relative to thetube, the wire can come into contact with the sharp edge, and be cut(FIG. 34(b)). Thus by altering the relative positions of tube andcapillary, wire can be cut when needed. In FIGS. 34(a) and 34(b), thetube has remained fixed and the capillary has moved; however, in someembodiment variations, this is inverted, or both the capillary and tubemove. In some embodiment variations, the entire lower edge of thesupport tube is not sharpened; the wire contacts the unsharpened regionin normal operation, but the tube is rotated to bring the sharp regioninto contact with the wire, allowing it (or causing/enhancing it, as aresult of the rotation) to be cut. In some embodiment variations, thetube is rotated sufficiently rapidly, cutting through the wire much likea hole saw; its edge may comprise teeth, diamond particles, etc.

FIG. 35 depicts an approach used in some embodiments for cutting wireissuing from an external capillary such as that in FIG. 29(a), 29(b),30(a), 30(b), or 30(c), in which the nozzle tip itself provides therequired cutting action. The nozzle is capable of rotating through asmall angle, and surrounding the nozzle tip is a fixed sleeve, which maybe tapered in shape. In some embodiment variations, the sleeve rotatesand the nozzle tip is fixed, or both rotate. The lower surface of thetip is furnished with an inner guide, comprising a groove for the wire(in practice the inner guide may be at located at a larger radius thanshown). The lower surface of the sleeve is provided with an outer guide,also comprising a wire groove. The bottom of each groove may be set to aheight that controls the vertical position of the wire within theextrudate, or may be set to not interfere with the wire position as setby an external capillary. The wire may be retained in the guidesmagnetically, in some embodiment variations.

The inner edge of the outer guide is in close proximity to the outeredge of the inner guide. At a particular orientation of the tip, the twogrooves can be substantially aligned. If a wire is placed in the grooveand the tip rotated, the wire can be cut by the shearing action of thetwo guides moving relatively. In some embodiment variations, only asingle guide may be used, simply to guide the wire into the polymer atthe desired position. In some embodiment variations, a single outerguide is provided, which may be capable of both rotation and axialtranslation, thus controlling the position of the wire entering theextrudate. By cutting the wire after it has passed through thecapillary, burrs and distortions introduced by cutting may be easilyaccommodated. In some embodiment variations, the inner guide is rotatedthrough a smaller angle and/or the space between inner and outer guidesis larger, and or radiused edges are used (e.g., cylindrical pins), soas to clamp or deform but not cut the wire. This can in some embodimentsallow intentionally deforming the end of the wire to enhance anchoringin the polymer, for example. Such an arrangement also allows forming thewire into a serpentine shape, bending the wire with tight radii toobtain sharp turns, etc. In some embodiment variations, the guides both(simultaneously or sequentially) cut the wire and shape the end of thewire upstream of the cut, deforming it plastically so it will be moresecurely anchored in the solidified polymer.

When depositing extrudate into a closed loop, the guides shown,protruding below the nozzle tip, may contact already-deposited andsolidified polymer just as the loop is closed. This may not an issue, inthat the inner guide is heated and the outer guide may be heated. Thus,the guides may re-melt the polymer (e.g., if the nozzle motion is slowedtoward the origin of the loop), avoiding a collision, though possiblyleaving a small defect. In some embodiment variations, the guides may berecessed further into the nozzle and sleeve, or be retractable. In someembodiment variations, the outer guide may also be rotatable. Then, theinner and outer guides may be rotated away from the origin of the loopto avoid contact.

In FIG. 36, a nozzle used in some embodiments and similar to that ofFIG. 35 is shown. Here, the wire guides are provided with holes in lieuof grooves, through which the wire is fed. In practice, the edges of thegrooves may be radiused to minimize damage to the wire. In someembodiment variations, one hole and one groove is provided. As before,the wire can be cut or clamped by this arrangement. In addition, byallowing the sleeve (and/or tip) to translate axially, the wire can bebent in complex 3-D shapes. For example, the wire may be bent so that itcan better follow the curve of the extrudate, especially if the wire isnot particularly soft, or is of a larger cross section and thus,stiffer. Or, the wire may be given an intentional residual stress insome direction so that it can preload a portion of the fabricatedobject. Or, if the wire has developed a curvature in the process ofdispensing from the capillary that would cause residual stress in thefabricated object, it can be bent so as to straighten it out again. Thenozzle of FIG. 36 may also be used for many of these purposes. Bendingby the nozzle may best be achieved by rapid, intermittent motion of thesleeve and/or nozzle, moving in a reciprocating fashion in translationand/or rotation. In this way, a closely-spaced series of micro-bends areproduced in the wire, but when the holes are aligned in between suchbends, the wire is still able to be fed through the holes with minimalfriction. In some embodiment variations, additional wire guides may beprovided, such as guides located diagonally opposite those shown inFIGS. 35-36. In the case of multiple guides, some may be designed forcutting wire (e.g., with sharper edges, or with the inner and outerguides in closer proximity when aligned, to provide shearing), whileothers may be designed for bending wire (e.g., with rounder edges, orwith the inner and outer guides further from one another). Guides may beshaped so as to minimally disturb the molten polymer through which theypass.

FIG. 37 depicts a cross sectional elevation view of an embodimentwherein an angled tunnel is provided in the nozzle to serve as acapillary to deliver the filament. As with the external capillaries ofFIGS. 29(a), 29(b), 30(a), 30(b), and 30(c), in this configuration thefilament need not be redirected through as large an angle as with acapillary that is parallel to the nozzle axis.

FIGS. 38(a), 38(b), 38(c), and 38(d) depict aspects of printheads usedin some embodiments wherein the axes of the capillary and nozzle aresubstantially parallel as, for example, in FIGS. 5(a), 5(b), 5(c), and5(d), and which promote the production of extrudates with embeddedfilament wherein the extrudates fully enclose the filament. FIG. 38(a)is an elevation cross sectional view of a nozzle wherein the bottom ofthe nozzle is oriented at an angle alpha <90° from the nozzle axis,tilted in the direction of printhead motion. Such a nozzle can providemore flow of polymer to the upper region of the extrudate, helping toclose any trench or smooth any seam that may be produced by the wireentering the extrudate, especially if the wire touches or approaches theinside of the nozzle. FIG. 38(b) is an elevation cross-sectional view ofa nozzle in which the bottom surface is unusually broad, eitheromnidirectionally as shown, or in the trailing direction (oppositenozzle motion). The prolonged time of contact between extrudate andnozzle surface can help keep the extrudate flowable for a longer time,facilitating closing or trenches and smoothing of seams.

FIG. 38(c) is a plan view of a capillary substantially parallel in axisto the nozzle axis (not shown). Wire is fed through the capillaryaxially. The capillary has a streamlined shape which can minimizedisruption of the extrudate through which it passes as the nozzle moves,and help prevent any “splitting” of the molten polymer stream by thecapillary. FIG. 38(d) is a plan view of a capillary substantiallyparallel in axis to the nozzle axis (not shown). Wire is fed through thecapillary axially. As the nozzle moves in the direction shown, polymeris extruded from the annular region between capillary and nozzleorifice. To the extent that the flow of polymer is “split” by thecapillary, also provided are two deflectors at least a portion of whichextends below the nozzle, and which force the twin extrudate streamstogether and to merge. In some embodiment variations, grooves orprojections in the bottom of the nozzle can also provide this function.In some embodiments, polymer flow around the wire (e.g., for larger sizewires) may be improved by vibrating the wire (e.g., by vibrating thecapillary), by heating the wire, by heating the polymer above the normalextrusion temperature, or by rapidly twisting and untwisting over alimited angular range (e.g., square filament twisted using a capillarywith a square lumen rotated about its longitudinal axis), for example.

FIG. 39 depicts a plan view sequential schematic illustrating thedeposition of an extrudate along a curved, U-shaped path in someembodiments, using a nozzle equipped with a capillary whose axis issubstantially parallel to the nozzle axis. The capillary can betranslated perpendicular to the direction in which the nozzle is moving.When the nozzle is at nozzle position 1, the path is straight and thecapillary is centered within the nozzle so as to center the wire withinthe extrudate. At position 2, the path remains straight, with thecapillary centered. However, at positions 3-5, the path has becomecurved with a particular radius. The desired wire shape, along thecenterline of the extrudate, is shown in finely-dashed lines in thefigure. If the capillary remains centered in the nozzle as at positions1 and 2, the wire—once extended from the capillary—may have a highenough yield strength that bending it leaves it with a residual stress.This stress thus causes the wire to spring back to a larger radius,which can cause it to depart from the desired shape (e.g., not remainsubstantially centered in the extrudate), and may also distort the shapeof the surrounding polymer, or damage the polymer (e.g., tearing throughit). To mitigate this, the capillary may be offset from the nozzlecenter toward the center of curvature of the path, as shown by thearrows at positions 3-5, over-bending the wire so as to compensate forthe springback effect. The amount of offset may vary with the radius ofcurvature of the path (e.g., more offset for a smaller radius). Once thenozzle has reached position 6, and again at position 7, the capillarycan again be located at the center of the nozzle.

In an alternative situation, certain wires and other filaments (e.g.,optical fibers) beneficial to incorporate into the extruded polymer havea minimum bend radius. If the bend radius of such a fiber, when lyingalong the centerline, would be too small, the capillary may be offsetaway from the center of curvature so that the bend radius for the fiberis larger. Although the fiber would no longer be centered in theextrudate, this may be acceptable.

FIGS. 40(a), 40(b), 40(c), and 40(d) depict in plan view the behavior ofan external capillary used in some embodiments. As shown, as the nozzlemoves through a U-shaped path in FIGS. 40(a), 40(b), 40(c), and 40(d),the capillary axis is reoriented to remain substantially parallel to thenozzle velocity vector (or if the printed object is moving, thensubstantially parallel to the object movement). More precisely, thelongitudinal axis of the capillary lumen nearest the nozzle ismaintained in a plane that is perpendicular to the substrate,substantially coincident with the nozzle axis, and substantiallyparallel to the component (in the plane parallel to the substrate) ofthe instantaneous velocity of the nozzle relative to the substrate.

As already described with respect to FIG. 39, in which an internalcapillary is offset to compensate for wire spring-back, an externalcapillary such as that shown in FIGS. 40(a), 40(b), 40(c), and 40(d) mayin some embodiments use the approach to reducing spring-back shown inFIGS. 41(a), 41(b), 41(c), and 41(d). In FIG. 41(a), the nozzle istravelling along a straight line and the capillary is parallel to thenozzle velocity vector. However, in FIG. 41(b), the nozzle is travellingin a curved path. While the wire may be soft and ductile (e.g., annealednickel, copper, gold, aluminum, silver), spring-back may still be anissue. To over-bend the wire and reduce spring-back, in someembodiments, the capillary may be over-rotated through an “overbendangle” relative to the velocity vector, and/or in some embodiments, thecapillary may be translated in such a way as to over-bend the wire. Ifin lieu of the nozzle moving in the X/Y plane, the nozzle is stationaryand the fabricated object is translating and rotating, then the objectwould normally be rotated as it translates in X and Y. Without overbendcompensation, the rotation angle may be that which makes the X/Yvelocity vector parallel to the capillary. With overbend compensation,the angle would be larger by the overbend angle, providing additionalrotation toward the center of the curved path. Thus if the path isS-shaped, the rotation might be first more clockwise than needed to makethe capillary parallel to the velocity vector, and later, morecounterclockwise. The overbend angle may vary with the radius of thecurve (e.g., increase with decreasing radius, to provide additionaloverbending). In some embodiment variations, the capillary is translatedlaterally as well as, or in lieu of, over-rotating. Approximatetranslation along the Y axis can be achieved, for example, with thecapillary of FIGS. 29(b), 30(a), 30(b), and 30(c), by twisting thecapillary about an axis parallel to its straight section. In someembodiments, overbending or pre-stressing of the wire may be achieved byrotating (continuously or intermittently) either the inner guide orhole, outer guide or hole, or both, using a nozzle similar to that shownin FIGS. 35-36. In some embodiments, adjusting nozzle speed when formingextrudates of different radii can help to ensure the wire remains in thedesired position and with the desired (e.g., zero) residual stress.Other methods of correcting for wire position within the extrudateinclude changing the wire feed rate as a function of extrudate radius.

FIG. 42 is an isometric schematic view of apparatus used in someembodiments wherein the printhead moves in the Z direction and theplatform on which the object is built rotates and translates in X and Y.The apparatus comprises linear X-axis and Y-axis stages stacked in anX/Y configuration and capped by a build platform. These are rotated by atheta/rotary stage, with wiring to the X/Y stages provided through sliprings in some embodiments. Also provided, and mounted on the same frame(not shown) as the theta stage, is a linear Z-axis stage to which aprinthead with nozzle is mounted through a support bracket. In someembodiment variations, two Z-axis stages may be provided, with theprinthead mounted on a member raised and lowered by both stages. In someembodiment variations, the axis of rotation of the theta stage is set tocorrespond to the axis of the nozzle (or more precisely, the thetarotation axis is made coaxial with the axis of the (typicallycylindrical) nozzle orifice). If so, then rotation of the fabricatedobject is equivalent to a rotation of the printhead about its axis, interms of relative motion. Thus, for example, an asymmetric nozzle suchas in FIG. 35 or 38(a), or an external capillary as in FIGS. 30(a),30(b), and 30(c) is provided, then rotation of the theta stage may beused to achieve the desired relationship between the nozzle orientationor capillary axis to the instantaneous velocity of the fabricatedobject, as determined by the motion of the X/Y stages. However, in someembodiment variations, the axis of the theta stage is offset from thenozzle axis. When depositing portions of the object having no embeddedfilament (e.g., polymer alone) using an asymmetric printhead (e.g.,having at least one external capillary, or having a capillary parallelbut not collinear with the nozzle axis), no rotation may be necessary,and the X/Y stages provide the primary motion when forming a layer.

In some embodiments wherein the nozzle or an associated component of theprinthead must rotate to remain at the same orientation to the extrudatepath as it follows a curve (e.g., when the nozzle is asymmetric as inthe embodiment shown in FIG. 35 and the fabricated object is not rotatedas with the embodiment of FIG. 42), a printhead having a spinning nozzlemay be used. FIG. 43 depicts a cross-sectional elevation view of such aprinthead, in this example one configured to deliver two materials-purepolymer and ECPC; the printhead also incorporate a capillary coaxialwith the nozzle to deliver wire. The upper, non-rotating portion of theprinthead comprises two vertical channels and/or liquifiers throughwhich the two materials can each flow downwards toward the interfacebetween the upper and lower portion of the printhead. The lower portionhas two concentric, circular channels on its upper, mating surface—onefor the pure polymer and one for ECPC. This surface, along with thelower mating surface of the upper portion may be machined (e.g., groundor lapped) to be very flat and smooth, minimizing leakage between upperand lower portions. Or in some embodiment variations, O-rings or otherseals may be used. To keep the two portions in intimate contact andguide the rotation of the lower portion, in some embodiment variations ahollow shaft fit into the lower portion passes through a bore in theupper portion (which may be lined with a suitable bushing material),where it can be preloaded upwards (e.g., using a spring), pulling thelower and upper portions together. Though the hollow shaft the capillaryand wire can pass en route to the nozzle chamber. Fluid entering thecircular channels normally fills the entire annular space of thechannels. Each circular channel communicates with at least one lowervertical channel which itself communicates with a horizontal channel(the horizontal channel can be drilled from the outside and partiallyplugged, or the lower portion may be fabricated using additivemanufacturing). Fluid exiting the horizontal channels enters the nozzlechamber, from which it is extruded. The lower portion is free to rotateas needed, driven, for example, by a belt or drive gear (neither shown).

In some embodiments wherein at least one external capillary is used(e.g., when the fabricated object is not rotated as with the embodimentof FIG. 42) the capillary and supply (e.g., spool) of filament may berotated around the nozzle (by a suitable actuator) as is needed toorient the capillary (e.g., FIGS. 40(a), 40(b), 40(c), 40(d), 41 (a),41(b), 41(c), and 41(d)). FIG. 44 depicts a plan view of a printhead(many components of which are omitted for clarity) wherein the filamentsupply is in the form of a coil surrounding the nozzle. A benefit ofthis configuration vs. using a spool of material to one side of thenozzle is the relatively well-balanced rotating element and therelatively large bending radius of the filament that is practical,facilitating use of filaments which cannot tolerate or become distortedby bending with a small radius, such as optical fibers. Moreover, suchan arrangement avoids excessive plastic deformation (and residualstress) of soft filaments (e.g., annealed Ni wire) by maximizing thewire coil diameter. In some embodiment variations, a plate supports thecoil, and the capillary is fixed to the plate. To re-orient thecapillary, the plate is rotated. As filament is pulled through thecapillary (if anchored) and/or fed (e.g., by a mechanism similar to thatof FIGS. 32(a) and 32(b)) toward the nozzle and cut to length (e.g., bya mechanism similar to that of FIGS. 33(a), 33(b), 33(c), 33(d), and33(e)), it is drawn from the coil into the capillary. In some embodimentvariations, as shown in the figure, the coil of filament is supported bya turntable which rotates independently of the plate (e.g., on abearing) as filament is fed, minimizing frictional drag between coil andplate.

FIG. 45 are plan views of printheads (of which many components, such asfilament supply spools, are omitted for clarity) having multipleexternal capillaries delivering multiple filaments to allow fabricationin some embodiments using multiple filaments (e.g., multiple filamentsincorporated into a single fabricated object). While multiplecapillaries can be incorporated within the nozzle in some embodiments,there is generally more space available for this when the capillariesare external. In the figure, four capillaries are provided, each with adifferent filament; in practice, fewer or more capillaries can be used.A wide variety of such filaments, both metal and nonmetal, can be usedsuch as copper wire for coils, nickel wire for magnetic cores andarmatures, optical fiber for lighting and communication, glass or carbonfiber (individual fibers or tow) for mechanical properties enhancement,coaxial cable for high-frequency or noise-sensitive signal transmission,and resistance wire such as nickel-chromium or carbon fiber for heatingor to form resistors needed in circuits and devices. In some embodimentsobjects may be affixed to wire (in some cases shaped like beads whichsurround the wire) and become embedded/encapsulated along with them.Different sizes and shapes (e.g., rectangular, square, circular,elliptical) may also be used. In FIG. 45(a), a linear stage that canmove along the Y axis allows the capillaries to be brought intoalignment with the nozzle, one at a time. In some embodiment variations,a rotary stage can be used instead, with the capillaries arranged atdifferent orientations, pointing outwards (e.g., in a turretconfiguration). In FIG. 45(b), the multiple capillaries are arranged atdifferent orientations surrounding the nozzle. In some embodimentvariations (e.g., those in which the fabricated object does not rotate),the capillaries may be rotated relative to the nozzle both to a) selectthe capillary required at a given time, and b) to orient the capillaryrelative to the nozzle velocity vector. For example, parallel to it asin FIGS. 40(a), 40(b), 40(c), and 40(d), or at the overbend angle as inFIGS. 41(a), 41(b), 41(c), and 41(d). In some embodiment variations(e.g., with the configuration of FIG. 42), the capillaries of FIG. 45(b)do not rotate relative to the nozzle; rather, the fabricated objectrotates relative to the capillaries, both to a) select the capillaryrequired at a given time, and b) to orient the capillary relative to thenozzle velocity vector. In the configuration of FIG. 45(b), in someembodiment variations, multiple filaments can be coiled to surround thenozzle as with FIG. 44. In some embodiments, cores and other elementssuch as in FIG. 12 may be wound using wire from capillaries that are notaligned with the nozzle, such as Capillary 4 in FIGS. 45(a) and 45(b).

FIGS. 46(a), 46(b), and 46(c) are plan views illustrating a rectangularnozzle orifice used in some embodiments. While round orifices aretypically used in FDM since they produce similar extrudate widthsregardless of the direction of nozzle (or fabricated object) motion,with the ability to rotate the nozzle (e.g. as in FIG. 43) or thefabricated object (e.g., as in FIG. 42), the use of nozzles that are notrotationally symmetric becomes feasible and useful in some embodiments.For example, a rectangular nozzle can be used to produce an extrudatewith sidewalls that are flatter than are produced by a circular nozzle,which tends to produce curved sidewalls. A vertical wall comprisingmultiple layers of extrudate normally exhibits a roughness associatedwith the curved sidewalls. Such a wall, when built from extrudates withflatter sidewalls, can be significantly smoother. Another benefit offlat sidewalls is improved visualization of filament embedded within theextrudate, with less refractive distortion. Thus, measurement in realtime of filament vertical position within the extrudate by imaging thefilament with a video microscope through the sidewall may beaccomplished more easily, facilitating dynamic, closed-loop adjustmentof the position. In FIGS. 46(a), 46(b), and 46(c), a nozzle with arectangular orifice having different width and height is shown,illustrating another feature of rotationally asymmetric nozzles: theability to vary extrudate width. FIG. 46(a) shows a rectangular orificewhich is oriented so its narrower dimension is perpendicular to nozzlemotion, while FIG. 46(b) shows the same orifice oriented so its widerdimension is perpendicular to nozzle motion. As can be seen, the widthof the extrudate can be varied widely. It can be useful, for example, todeposit a narrow extrudate to better define small features, whiledepositing a wide extrudate when only larger features are needed, or torapidly fill in broad regions (e.g., the internal volume of thefabricated object, or an up- or down-facing horizontal surface, or toadjust the amount of polymer “insulation” on the wire (e.g., reducingthe insulation thickness to allow thinner layers or for coils, allowingfor more turns). FIG. 46(c) shows the orifice oriented relative at anangle between the angles of FIGS. 46(a) and 46(b), such that theextrudate width is intermediate in width and a function of the angle A.in some embodiment variations, rather than a rectangular orifice, othershapes may be used, such as ellipses.

FIGS. 47(a) and 47(b) are plan views depicting another orifice used insome embodiments that is not rotationally symmetric, in this caserectangular and equipped with at least one sliding shutter. Whilemulti-leaf camera lens-like diaphragms are difficult to implement due tothe small size required, as well as freedom from leakage and mechanicalreliability, if the orifice is asymmetric, a single sliding shutter asin FIG. 47(a) can be used to regulate extrudate width. If desired, asecond shutter may be incorporated as in FIG. 47(b).

As already described, vertical, Z-axis junctions between wires may beproduced by overlapping regions of ECPC on adjacent layers. FIG. 48illustrates in plan view a junction used in some embodiments in whichthe wires are parallel, but are separated by an angle B, which can rangefrom 0 to 360°. The ECPC regions associated with these wires arethemselves not parallel, yet overlap sufficiently to provide adequateconductivity. ECPC regions may be rectangular as shown, or may havealternative shapes, e.g., circular.

FDM using very soft elastomers (e.g., 5-60 Shore A durometer) can bechallenging if the material is provided in conventional filament form,fed into a liquifier by rollers as is conventionally the case. As hasbeen described in [Elkins 1997], soft filaments may buckle when pushedby the rollers, a problem exacerbated if there is any softening of thematerial prior to entering the liquifier. A requirement for extruders isFDM is the ability to precisely control feed rate, as well as theability to retract (i.e., suck back) the extrudate, as may be donebefore making jumps from one X/Y location on the layer to another. Insome embodiments, alternative extruders for FDM printheads which areable to extrude very soft thermoplastic elastomers may be used. FIG. 49depicts a cross-sectional elevation view of a printhead used in someembodiments based on a screw extruder that comprises a hopper forpolymer (e.g., in pellet, powder, or granule form), a screw turnedwithin a barrel by a motor, and a nozzle (e.g., below the screw). Insome embodiment variations an actuated piston is provided within acylinder between the screw and nozzle orifice. Retraction of the pistoncreates suction that retracts molten material within the nozzle,providing retraction. In some embodiments, in lieu of a piston andcylinder, a diaphragm, bellows, screw, or other means of rapidlycreating a volumetric change or suction may be used. In some embodimentvariations, a constriction is provided between the screw and piston suchthat retraction of the piston preferentially causes inward movement ofmaterial in the nozzle, and less so movement of material surrounding thescrew. In some embodiment variations (e.g., to extrude ECPC, the barrelis vented in a region after the polymer has substantially melted, in alower pressure region of the screw. In this region, a hopper containingpowder above a screen is provided; a vibrator may be attached to thehopper, along with a compliant mount (e.g., a bellows, or the hopperitself may be compliant) such that when the vibrator is actuated, powdersteadily flows through the screen, but not otherwise. Powder thus ismixed with polymer by the screw prior to extrusion. Using suchapparatus, powder may be incorporated into polymer only where ECPC isneeded, otherwise extruding pure polymer. Powder can be introduced bythe control system “looking ahead” in the data file that controls thefabrication process to determine where ECPC is needed, since there is adelay from the moment powder is introduced until ECPC is extruded.Polymer composites with variable concentrations of powder may also bedelivered in some embodiment variations; e.g., using variable amounts ofconductive powder to fabricate resistors with different resistivities,sensitive strain gauges (e.g., for robot joint position feedback) whoseconcentration of powder is in the steep region of the conductivity vs.concentration curve, or using variable amounts of another powder tolocally change the strength or elastic modulus of the polymer.

FIG. 50 depicts a cross-sectional elevation view of a printhead used insome embodiments comprising a double-drum extruder intended for use inFDM of soft elastomers. Filament is preferably provided in flat,substantially rectangular ribbon form, though filament with circular orother cross-sectional shapes can also be used. The filament is drawninto the heated block of the extruder by the motion of twocounter-rotating drums. These may in some embodiment variations becooled so as to avoid prematurely softening the filament by contact withthe drums, potentially reducing traction on the filament. Filamentbrought into contact with the heated block, e.g., at a keel, is meltedand transported by viscous drag around one drum or the other until itreaches a wiper. Molten polymer then continues to flow through flowchannels until it reaches a common chamber on its way to the nozzle. Insome embodiment variations, an actuated piston and cylinder are providedbetween chamber and orifice as in FIG. 49 for polymer retraction, whilein some embodiments drum rotation is reversed. In some embodimentvariations a constriction is also provided to allow the piston topreferentially retract polymer in the nozzle.

In some embodiments, especially those using very soft materials such asChronoprene with a durometer of 5 Shore A, polymer filament with across-sectional area comparable to that of extrudate and having apre-embedded wire of small diameter is provided, such that by pulling onthe wire, the filament can be fed into the printhead. In regions of thepart in which no wire is desired, the wire can be spooled up or ejected.In some embodiments, materials are pulled into the liquifier bypressurizing the material supply and/or at least partially evacuatingthe build chamber.

FIG. 51 depicts cross-sectional isometric views of a centrifugalextruder used in some embodiments, either as a part of a printhead, orfor the creation of filament. FIG. 51(a) is a cross-sectional isometricwith a vertical cross-section plane, while in FIG. 51(b) the plane ishorizontal. The centrifugal extruder comprises an extruder body, ahopper for pellets or other polymer feedstock, a rapidly-spinning disk,and an output port. In some embodiment variations, the lower part of thehopper comprises a pre-melt region with heating, and a porous screen,such that feedstock is prevented from reaching the disk until it is atleast partially melted and passes through the screen. In some embodimentvariations the disk, extruder body, and/or output port are heated.Material reaching the surface of the disk is propelled to the edges ofthe disk by centrifugal force, where it may be further melted by contactwith the extruder body walls. Melted material is also propelled out ofthe output port. In some embodiment variations, powder additives (e.g.,metal powder) may be added (e.g., sprinkled onto) the molten material asit forms a relatively thin layer on the rotating disk, assisting withmixing. In some embodiment variations, the surface of the disk incontact with the polymer is provided with features (e.g., vanes, pins)that slow the motion of the polymer toward the disk edge, promotingmixing and/or melting. In some embodiment variations in which thecentrifugal extruder is used in an FDM printhead, an actuated piston andcylinder are provided between disk and output port (leading to a nozzle)for polymer retraction, and in some embodiment variations a constrictionis also provided between disk and piston to allow the piston topreferentially retract polymer in the nozzle.

FIG. 52 depicts an isometric view of a wire that is “stapled” accordingto some embodiments. The “staple” comprises a bent region of the wirethat causes it to descend into at least one previous layer (not shown)and then return, thus anchoring it well. In some embodiment variations,staples are used to better anchor wire when the extrudate (not shown)must turn a sharp corner or in general, conform to a smaller radius. Thestaple may be more gradual than that shown in the figure. Wire may beformed into staples by the vertical motion of a capillary through whichit passes. Stapling is used in some embodiment variations to provide anelectrical connection between wire in the current layer and that inanother layer, e.g., by locating the staple in ECPC in the previouslayer(s). In some embodiment variations, staples are used to betterconstrain wire that is stressed, forcing it into the desired shape, anddistributing the stress over multiple layers.

FIGS. 53(a), 53(b), 53(c), 53(d), and 53(e) depict cross-sectionalelevation views of an anchoring method used in some embodiments toanchor the end of wire within a previously-formed layer (layer N−1)(e.g., in a region filled with ECPC). In FIG. 53(a), a wire is providedwithin a capillary; the capillary may be oriented vertically as shown,or non-perpendicular to the layer. In FIG. 53(b), the wire has been bentat least slightly by contact with a fixed stop (e.g., by moving theprinthead horizontally). In FIG. 53(c), the wire has been further bentby lowering the capillary and wire so as to press the latter against theprevious layer (or by further action of the stop). In FIG. 53(d), thecapillary has been lowered into the previous layer, forcing the wire tobend into a hook/barb/“J” shape. In general, the penetration of wireinto polymer may be enhanced by heating the wire (e.g., by heating thecapillary) enough to allow for cooling of the wire before penetration,vibrating it, and/or twisting it (e.g., by twisting the capillary orprinthead). Penetration of the capillary into the polymer, as a means ofdelivering the wire for anchoring, may be enhanced by heating thecapillary, twisting it, vibrating it, and provided a sharp and/ortoothed penetrating tip. Finally, in FIG. 53(e), the capillary has beenwithdrawn over the wire, leaving the wire securely anchored in theprevious layer by virtue of the shape of the end of the wire resistingextraction.

In some embodiments using an external capillary, the wire emerging fromthe capillary may be forced into the previous layer by a needle (e.g.,with a groove/bifurcated tip to accept the wire) which penetrates intothe previous layer. The needle may be heated, vibrated using ultrasonicenergy. It may be located between the capillary and the nozzlecenterline.

FIGS. 54(a), 54(b), 54(c), and 54(d) depict cross-sectional elevationviews of an anchoring method used in some embodiments to help anchor theend of wire within the current layer, which may be useful, especiallywith an external capillary. In FIG. 54(a), a wire extends from acapillary. The wire may be horizontal as shown (e.g., passing through anexternal capillary), or oriented at another angle. In FIG. 54(b), thewire has been squeezed between two parts of a die, which may includeinternal features that can plastically deform the wire. In someembodiment variations, the die is attached to the machine, e.g., off tothe side of the build area, such that the printhead can move to reachit. In other embodiment variations, the die may be fastened to theprinthead (e.g., it may be positioned above the bottom of the nozzle asin FIGS. 30(a), 30(b), and 30(c) such that when the capillary isretracted the wire can be extended into the die and the die closed. InFIG. 54(c), the wire has been removed from the die, and is now deformedinto a non-straight shape. In FIG. 54(d), the wire end is embedded inpolymer which has been deposited around it; the shape of its end anchorsthe wire, resisting pull-out. Moreover, the deformed shape of the wirecan increase contact area with the ECPC.

FIGS. 55(a) and 55(b) depict two cross-sectional elevation views of afabricated object such as a cube in the process of being fabricated. Inthe prior-art FDM process shown in FIG. 55(a), extruding structuralmaterial to form the top of the cube requires that either structuralmaterial (later removed) or support material (e.g., soluble) be providedwithin the cube so as to provide a substrate onto which the extrudatecan be deposited. In contrast to this, FIG. 55(b) depicts fabricatingthe top of the cube using a bridging method according to someembodiments, wherein a filament is simultaneously embedded andincorporated into the extrudate as material issues from the nozzle. Thefilament is typically under a slight tension, and by virtue of itsmechanical strength, and the tendency of the molten material to cling toit due to surface tension and viscosity effects, the molten material cansolidify around the filament without sagging or simply falling into theopen space below. Indeed, materials with viscosities that are typicallytoo low to extrude well such as waxes and molten metals may beco-extruded with a filament to which they cling and which controls theirshape and position. In some embodiment variations, this effect isexacerbated by using a filament of high thermal conductivity, or whichis cooled prior to delivery, or which is in the form of a tube that isactively cooled by circulating fluid. The filament may have usefulproperties other than supporting the extrudate; it may also provideelectrical circuitry, for example. This unique capability of FEAM tobridge open spaces without the need for structural support enableslayered fabrication with fewer or no supports, speeding up both thefabrication and support removal processes, reducing material usage andwaste, and reducing cost. It can also enable new geometries, e.g.,structures with shapes for which support removal is difficult orimpossible. For example, fluidic chambers, channels, and manifolds maybe easier to build this way. Reduced need for supports also helps toenable high volume production of objects, since support removalotherwise can be time-consuming and costly.

FIG. 56(a) depicts an isometric view of a curved 3-D structure that canbe fabricated in some embodiments by moving the nozzle simultaneously inthe X, Y, and Z axes. For example, the top of the shape in FIGS. 55(a)and 55(b) may, instead of being planar, be a curved structure such asthis. To aid in the production of such shapes without supportingstructures or support material, and/or to reinforce the extrudedmaterial, filament may be delivered where needed into the moltenmaterial as it is extruded, as in FIG. 55(b), resulting in afilament/polymer composite as in FIG. 56(b). The direction of thefilament may be varied throughout the structure. In some embodimentvariations, the wire may be bent in three dimensions (e.g., by a nozzlesuch as that of FIG. 36) to conform to the desired 3-D path. 3-Dstructures produced by this approach may comprise single layers, orcomprise multiple layers, each having a similar shape, or a differentshape (e.g., creating voids between layers). In some cases, non-planarstructures can be stronger or stiffer than planar structures, requireless support material, and be faster to fabricate. If they includeconductive wire, they can also provide the required electrical pathswith a minimal number of junctions, reducing overall resistance of thepath. With the ability to create a composite such as that in FIG. 56(b)from wire and elastomer, comes the ability to create stretchableelectronic circuits in which the wire and elastomer can undulate (e.g.,in a serpentine manner) in the vertical plane and in complex 3-Dconfigurations, not merely in one plane.

In some embodiments, PMPCs incorporated into an object may be magnetizedafter the object is fabricated, e.g., by placing at least part of theobject in a strong magnetic field. FIGS. 57(a), 57(b), 57(c), 57(d), and57(e) depict elevation views of a method and apparatus used in someembodiments of magnetizing PMPCs as they are deposited, either one orseveral layers at a time. This enables the creation of complex,additively-manufactured magnets, such as permanent magnets orelectromagnetics with unusual pole configurations which can createcomplex magnetic fields (e.g., Halbach arrays) for actuators andsensors, or encode data (e.g., for remote identification such as RFID,or authentication/anti-counterfeiting). In FIG. 57(a) a nozzle isdepositing a PMPC for layer N onto layer N−1. Located in the path of thenozzle is a cylindrical electromagnet; the location of this can bechanged dynamically so as the nozzle executes a motion along a curve,the magnet is always over the already-deposited material. When currentis passed through the electromagnet coil as in FIG. 57(b), a magnetizedregion of the PMPC, spanning one or more layers as desired, is producedin the vicinity of the electromagnet pole, with a desired north/southpolarity. Thus, the object being fabricated can include volumes whichare not magnetized, as well as those magnetized with either the NorthPole pointing upwards or downwards. FIGS. 57(c), 57(d), and 57(e) showan alternative electromagnet in the shape of a horseshoe also producingmagnetized regions. In this configuration, the magnetic flux passes outthrough one pole, through the PMPC, and back into the other pole. Insome embodiment variations, to provide a return path for flux the layerunderneath can contain a reasonably high concentration of soft magneticmaterial (but not necessarily be conductive) such as Fe or Ni particles.In some embodiments, two electromagnets are located on either side ofthe nozzle to magnetize the extrudate with a horizontal magnetizationaxis. In some embodiments, in lieu of a localized electromagnet, PMPC inone or more a layer may be magnetized after the layer is deposited,either heterogeneously or homogenously, by using a sliding or rolling“write” head, or a large magnetizer which simultaneously magnetizes PMPCon the entire layer.

FIGS. 58(a), 58(b), and 58(c) depict cross-sectional elevation views ofa method for embedding an integrated circuit such as a microprocessor oranalog device (or a MEMS device or other component or subassembly)within a structure produced using FEAM. In particular, since thedeposition temperature of thermoplastics may exceed the maximumtemperature of some devices, it can be important to avoid directlydepositing molten polymer on top of a device, especially if unpackaged(i.e., bare). In FIG. 58(a), the bare IC die has been mounted to asubstrate that is preferably thin, and has been wire bonded (e.g., usingthermosonic methods known to the art)—with wire running between IC andsubstrate bonding pads—to the substrate. An encapsulant, preferably witha low coefficient of thermal conductivity, may be applied to the die toprotect it and insulate it from molten polymer that in some embodimentvariations will be applied over the die. In FIG. 58(b), a cavity in theobject to receive the substrate has been prepared and in FIG. 58(c), thesubstrate has been placed (e.g., by automated pick-and-place equipment)into the cavity and ECPC has been deposited onto the substrate bondingpads to form a junction. The ECPC communicates with wire in most cases,electrically connecting the IC to the object being fabricated (e.g., arobot). Next, more layers may be deposited, either directly over theencapsulant, or leaving a cavity over the encapsulant to provide thermalinsulation. At least a portion of the subsequent layers may serve toretain the substrate in the cavity, e.g., at its edges, while in someembodiment variations, an adhesive (e.g. melted polymer) may bedeposited into the cavity or onto the bottom of the substrate before itis placed. In some embodiment variations, the top of the cavity can havesloping walls (e.g., at a 45° angle) so that no support material isrequired, while in other embodiment variations, the cavity can be closedby a bridge-type cap supported by filament as in FIGS. 55(a) and 55(b).In the latter case, encapsulant may be superfluous. In some embodimentvariations, the die is directly inserted into the cavity without asubstrate. In some embodiment variations in which less or no encapsulantis used, ECPC is directly deposited onto the IC bonding pads. In someembodiment variations, rather than being inserted into a cavity, thesubstrate or die is placed on top of the last layer and structure isbuilt around it. In some embodiment variations, the chip is insertedinto a cavity that is deep but narrow, such that the plane of the chipis vertical (orthogonal to the layer plane) or at another angle. In someembodiment variations, the die may be provided with bumps (e.g., solder)or studs (e.g., gold) through which a connection is made.

In some embodiments, the substrate or die is placed inverted comparedwith FIGS. 58(a), 58(b), and 58(c) as is shown in the cross-sectionalelevation views of FIGS. 59(a), 59(b), and 59(c), in which no substrateis used. In such embodiments, the bonding pads on the IC (or substrate)make contact with wire, solder, or ECPC (as shown) on a previous layer.In this orientation, the substrate, if used—especially if made from lowthermal conductivity material—can help insulate the die from the moltenpolymer. In FIG. 59(a), at least several layers have been fabricated,forming a cavity and comprising wire in electrical contact with ECPCpads. As shown in FIG. 59(b), the die is inverted and positioned so itsbonding pads (or conductive structures attached to its bonding pads,such as bumps or studs, not shown) are in mechanical and electricalcontact with the ECPC (or wire).

In some embodiment variations, the ECPC is reflowed (e.g., by localizedheating with a hot air jet or laser) to bond the ECPC to the die. Insome embodiments, the ECPC is composed of a lower melting point materialthan the surrounding insulating polymer, such that once the object isfabricated, the ECPC pads can be softened by heating the entire objectin an oven to a temperature sufficient to reflow the ECPC but not deformor damage the fabricated object. In some embodiment variations, aconductive adhesive is used to bond the IC bonding pads to the ECPC (ordirectly to exposed wires). In some embodiment variations, the ICbonding pads have affixed to them a protruding conductor (e.g., a shortpiece of bond wire) that can penetrate into the ECPC when the die ispressed against the ECPC pads, thus securing the die mechanically to theECPC pads and making a good electrical connection. In some embodimentvariations, a thermoset or air-drying conductive adhesive is used toconnect the IC bonding pads with the ECPC. In some embodimentvariations, pressure is used to press the IC bonding pads against theECPC. In some embodiment variations, the melting points of the “primary”ECPC (i.e., that used throughout the object for electrical junctions)and the (insulating) polymer are similar (e.g., the primary ECPC is afilled version of the insulating polymer), but the IC bonding pads arecoated with an second, “secondary” ECPC having a lower melting pointthan those and which can bond to the primary ECPC. The secondary ECPCcan be reflowed just before the die is inserted (e.g., by exposing it toa source of infrared energy) and can then solidly in contact with, andbond to, the primary ECPC. Or, the fabricated object can be baked in anoven at a temperature high enough to reflow the secondary ECPC and bondit to the primary ECPC, without reflowing the primary ECPC or thepolymer.

In FIG. 59(c), the cavity is capped by depositing a layer of polymerwith a core of filament over it in a “bridge” configuration (as in FIG.55(b)), such that the polymer does not come into contact with the die.In some embodiment variations, the cavity is capped by building a hollowregion (e.g., pyramidal) from polymer with walls at a steep enough angle(e.g., 45°) that no support material is needed. In some embodimentvariations, a thin layer of thermally insulating material is applied topolymer is applied to the rear of the die, and polymer is depositeddirectly onto it. In some embodiment variations, polymer is directlyapplied to the rear of the die but in a relatively thin “partial layer”(i.e., one thinner than a standard layer), so as not to overly heat it.This is then followed by other partial layers, or a layer of normalthickness, with at least one partial layer acting as insulation.

In some embodiments, thermal damage to sensitive components may bemitigated by other means. For example, limiting exposure time to themolten polymer by gradually deposit polymer over the component, andreturning to it multiple times while building up other areas of theobject is one option. Providing a metal heat sink made from wire can behelpful. Using components that already have a thermally-protectivepackage is an option, though requires more room for the component.Depositing polymer onto the component which incorporates gas bubbles isa possibility, thus reducing thermal mass and lowering thermalconductivity. Lastly, cooling the polymer using air or liquid jetsimmediately after deposition to solidify it can avoid the componenthaving enough time to heat to a temperature at which it will be damaged.

In some embodiments, devices such as integrated circuits may haveconductive leads pre-attached to them, and then be embedded intofabricated objects, such that junctions can be made between wires withinthe object and these leads, rather than between wires and device bondingpads. In some embodiments, small devices such as semiconductor devicesmay be connected to conductive leads and be directly embedded into theextrudate, in much the same way that plain filament is embedded. Forexample, a series of light emitting diode (LED) bare die, wired inseries, consists of alternating regions of wire and die; this may bedelivered into the molten extrudate (e.g., by a suitable capillary) andthe two wire ends connected to a power source. If the LEDs are wired inparallel, then two wires, with LED die spanning them like rungs on aladder, may similarly be embedded into an extrudate.

FIG. 60 depicts an isometric view of a discontinuous Z-axis coilfabricated according to some embodiments. Polymer with embedded wire isdeposited to form an open loop on each layer. Typically, the free endsof each loop terminate in a volume of ECPC, and the ECPC volumes onadjacent layers overlap to form junctions which allow current to flowfrom layer to layer. In the figure, current enters at the junction onthe topmost layer, and circulates in a clockwise direction on its way tothe output junction on the bottommost layer. Input and output are chosensomewhat arbitrary for clarity since coils are not polarized. Not shownare the wires connecting to these junctions; the input wire can belocated above or to the side of the input junction, while the outputwire can be located below or to the side of the output junction.Alternatively, the input and/or output wire can be continuous with thetop or bottom coil wire, respectively, eliminating the need for ECPCjunctions in those regions.

By comparison with FIG. 60, FIG. 61 depicts an isometric view of acontinuous helical coil fabricated according to some embodiments. Withthe printhead nozzle moving relative to the fabricated object in acoordinated X, Y, and Z motion, and an external capillary (and possibleguide tube, not shown) rotating as well, polymer and wire (here, shownto be square) are deposited to form helical turns of the coil, and noECPC is needed within the coil. As shown, the coil has all turns at aconstant radius. However, in some embodiment variations, having reachedthe last turn at the top of the coil, a downward-growing coil may beformed at a larger radius, outside (or inside) the turns already made,to provide additional windings (e.g., for larger inductance). Thisprocess may be continued for multiple radii. Moreover, the coil may betapered or otherwise made to vary in radius along its axis, and coilsmay have concave shapes as well as convex shapes typical ofconventionally-wound coils. In some embodiments, coils madediscontinuously as in FIG. 60 or continuously as in FIG. 61 may havenon-circular and non-cylindrical shapes, e.g., coils square in planview, or conically tapered in elevation view. In some embodiments,rather than move continuously in a helical fashion as in FIG. 61, theprinthead makes an almost-complete circle in one layer (retracting thecapillary if needed to avoid a collision with the beginning of thecircle), then jumps up to the next layer, without cutting and restartingthe wire.

FIGS. 62(a), 62(b), 62(c), 62(d), and 62(e) show cross-sectionalelevation views of steps according to some embodiments for fabricating acontinuous helical coil such as that of FIG. 61 that is embedded withina fabricated object. In FIG. 62(a), the last layer before fabricatingthe coil is being formed. In FIG. 62(b), the coil has been formedcontinuously, as in FIG. 61, e.g., using an external capillary to guidethe wire. In FIG. 62(c), the remaining portions of the layerssurrounding the coil are being formed; the cumulative thickness of theselayers may be slightly more than the height of the coil. As will be seenin FIG. 62(c), due to the finite width of the nozzle (which nonethelessmay be made narrower and/or more cylindrical than shown), polymer forthe remaining portions cannot be deposited immediately adjacent to thecoil, and an annular gap remains surrounding the coil. In FIGS. 62(d)and 62(e) this gap has in some embodiment variations been filled in withadditional polymer that spans multiple layers. The approach of buildinga structure continuously across multiple layers—or embedding an objectthat spans multiple layers—and then building up around it, can beapplied to making solenoid cores that are wound from wire, insertedbearings, etc.

FIGS. 63(a), 63(b), 63(c), 63(d), 63(e), and 63(f) show cross-sectionalelevation views of steps of an alternative approach according to someembodiments for fabricating a continuous helical coil that is embeddedwithin a fabricated object. In this case, a cavity (e.g., cylindrical)is created within the object, and the coil is fabricated within it. InFIG. 63(a), the cavity has been created. In FIG. 63(b), the nozzle andcapillary (e.g., internal capillary with axis parallel to that of thenozzle) has begun to deposit the first turn of the coil (both polymerand wire), and in FIG. 63(c), more of the turn is completed. In FIG.63(d), the entire coil has been completed. Again, due to the finitewidth of the nozzle, the coil cannot be deposited immediately adjacentto the walls of the cavity, and an annular gap remains surrounding thecoil. In FIGS. 63(e) and 63(f) the gap is filled in with additionalpolymer.

The approach of FIGS. 63(a), 63(b), 63(c), 63(d), 63(e), and 63(f) maynot be suitable for use using an external capillary of the kind shown inFIGS. 30(a), 30(b), and 30(c), due to interference between the capillaryand the wall of the cavity, so a capillary (e.g., internal) whose axisis parallel to that of the nozzle may be more appropriate. However, asshown in the plan view of FIG. 64, an external capillary and nozzle ofsuitable design can be used to create a continuous coil directlyadjacent to the wall of the cavity. The nozzle is elbow-shaped, so as tore-direct the flow of molten polymer to one side, and rotates and (ifnot centered on the cavity as shown) translates, to follow the innerwall as it deposits polymer extrudate. Meanwhile, a capillary that maybe curved at least in part in the horizontal (layer) plane is providedto distribute wire. The capillary rotates/translates along with thenozzle, and may be fixed to it. In the figure, the first partial turn ofthe coil has been formed at the bottom of the cavity (on top of layer M)while the nozzle and capillary rotate counterclockwise. With eachsuccessive turn, the nozzle/capillary is raised. Once the full height isreached (e.g., flush with, or below layer N), the nozzle/capillary maybe moved to a small radius and the process continued as they movedownwards toward layer M again. This may be continued further forsmaller radii. A similar nozzle, e.g., without the capillary, could beused in the case of FIGS. 62(a), 62(b), 62(c), 62(d), and 62(e) todeposit material more closely around the coil.

A bent (not necessarily 90°) nozzle similar to that of FIG. 64 but witha capillary whose axis is substantially parallel to the nozzle axis(e.g., internal) can also be used in some embodiments—as in theisometric view of FIG. 65—to form a continuous coil having an axis thatis horizontal (i.e., at 90° to the Z, or layer-stacking axis), or atother angles. Coils whose axes are not vertical may be generally usefulfor electromagnetic actuators and sensors.

FIGS. 66(a), 66(b), 66(c), and 66(d) depict a coil which has beenfabricated discontinuously in some embodiments as in FIG. 60 (however, acontinuously-fabricated coil such as that of FIG. 61 could also be used)with its axis vertical, and which is then rotated until its axis lies atanother angle (in this case, horizontal). The rotation can be stopped ata particular angle (e.g., by fabricating a suitable mechanical stop. Theprinthead or a specialized instrument on the FEAM machine can affect therotation during the build process, or the process can be interrupted ifneeded (and the rotation performed manually in some embodiments), andpolymer can be deposited after rotation to retain the coil in its newposition. FIG. 66(a) is an isometric view of the coil, showing portionsof the input and output leads which are in the same horizontal plane. Inthe plan view of FIG. 66(b), a bend axis is shown around which the leadscan be bent. In FIG. 66(c), the coil has been partly rotated by bendingthe leads around the bend axis, and in FIG. 66(d) the bending (assuminga 90° bend is desired) has been completed. In some embodiments, the bendaxis is elsewhere, and the leads may not be bent, though they may betwisted. Other structures than coils may be similarly rotated, forexample, armatures/plungers used in conjunction with coils to formsolenoid-type actuators.

FIGS. 67(a), 67(b), and 67(c) depict in cross-sectional elevation viewstwo approaches used in some embodiments to electrically connect wiresfrom one layer to another other than by using overlapping regions ofECPC or by using a joining method (e.g., thermosonic or laser bonding)to connect the wires. In FIG. 67(a), a wire is shown on layer N thatextends at its tip or anywhere along its length into a hole formed so asto span multiple layers from layer N to layer N+M. In FIG. 67(b), aconductive pin has been inserted into the hole, making contact with thewire on layer N and thus interconnecting layer N to the top of the layerstack. The pin preferably slightly deforms the wire to make goodcontact. If wires are provided on other layers (e.g., layer N+2) thatextend into the hole, they too can be contacted by the pin and beelectrically connected as well. The pin may be retained in the hole bypressure, adhesive, or other means, such as being sized to be a pressfit, or being heated so as to slightly melt and deform the surroundingpolymer. In FIG. 67(c), the wire in layer N extends into ECPC and aninterconnect wire delivered through a hole running from layer N+1 tolayer N+M enters the ECPC, thus connecting the two wires together with alow resistance.

FIGS. 68(a) and 68(b) are cross-sectional elevation views of a group oflayers comprising wires which are at least partly surrounded by ECPC.The ECPC regions are shown to overlap; thus electrical contact isestablished between the layers. In some embodiments, to further decreasethe resistance in this vertical interconnect, a wire or pin is insertedthrough the ECPC regions. In such a case, the ECPC is used to bridge theshort distance between wire and vertical wire, and the overallresistance can be reduced. The wire may be heated to aid insertion,twisted, etc. In some embodiment variations, the wire may be in the formof a small drill bit which drills through the ECPC volumes. In someembodiment variations, the wire is inserted (e.g., at an angle) throughECPC volumes which do not otherwise overlap.

FIGS. 69(a), 69(b), 69(c), 69(d), and 69(e) depict in cross-sectionalelevation views an approach to creating junctions between two layers inwhich ECPC is required only on the lower of the two layers. In FIG.69(a), layer N−1 comprises a first wire, a portion of which is within avolume of ECPC. A capillary is provided through which a second wire isfed. The nozzle, having already deposited polymer for a portion of layerN, has come to a stop or possibly slowed down. In FIG. 69(b), thecapillary and second wire have been lowered; the second wire is immobilewithin the capillary (e.g., clamped by the capillary) and about topenetrate the ECPC. In FIG. 69(c), the second wire has impaled the ECPC,forming a junction with the first wire. In FIG. 69(d) the capillary, nowfree to move without moving the second wire, has been raised (if neededto allow the nozzle to deposit polymer). In FIG. 69(e), the nozzle ismoving, bending the second wire, which remains anchored in the ECPC.

FIGS. 70(a), 70(b), and 70(c) depict a specialized pounce wheelarrangement for embedding filament, along the lines of that alreadydescribed in conjunction with FIGS. 13(a), 13(b), and 13(c). As shown inthe isometric view of FIG. 70(a), the wheel may comprise a hub andmultiple spokes. FIG. 70(b) depicts a single spoke in closeup view,showing a groove in some embodiment variations to accommodate thefilament. In the elevation view of FIG. 70(c), filament is pushed belowthe surface of a layer (e.g., of thermoplastic material) by the spokesof the wheel as the wheel rotates and moves. The wheel spoke length andposition may be optimized to push the filament approximately halfwayinto the layer. In some embodiment variations as shown, current ispassed from one spoke to another adjacent spoke through the (conductive)filament; the spokes can alternate between two terminals, labeledpositive and negative (though the polarity is not relevant), of a powersupply. By virtue of Joule heating, the filament is heated and moreeasily penetrates the layer. As shown in the figure, the filament may bein contact with more than two spokes at a time, such that all portionsof the wire that must penetrate the surface are heated. In the case oflayers of non-thermoplastic material, the wheel may simply serve toforce the filament below the surface, with no Joule heating provided. Insome embodiment variations, the spokes may be tapered so as to betterpenetrate the polymer. In some embodiment variations, the pounce wheelis ultrasonically vibrated to better embed the filament. The path alongwhich the wheel rolls may not be straight, so that wire to be embeddedalong curved paths; as such, the wheel may rotate relative to thefabricated object around an axis perpendicular to the layer (i.e.,vertical) or parallel to the local surface normal, or vice-versa (theobject may rotate).

FIG. 71 is a cross-sectional elevation view depicting a printheadfurnished with a gas inlet and in some embodiment variations, a porouselement, for the purpose of depositing an extrudate containing gasbubbles. The porous element (e.g., a sintered metal filter such as thosemade by Mott Corporation, Farmington, Conn., with a suitable, preferablysmall pore size) can help produce a large number of bubbles with thedesired size distribution. The gas may be injected into the printheadhigher up within its heated portion, not necessarily within the nozzleas shown. The process may be similar to that used in microcellularinjection molding, known to the art. Bubbles may be of air or of a gassuch as nitrogen. Injected bubbles may be used to alter the mechanicalproperties (e.g., elastic modulus, tensile strength) of the extrudedmaterial, on a smaller size scale than might be achieved by toolpathswhich leave voids in the fabricated structure. For example, a relativelyhigh-durometer elastomer may be given an effective hardness that issignificantly lower if it solidifies with internal voids such as wouldbe produced by entrapped gas (e.g., air) bubbles. Gas bubbles may alsobe used to modulate the appearance of the solidified extrudate. Forexample, a clear polymer may be made to look translucent or even opaquewhite, due to light scattering by the bubbles, if sufficiently small. Byvarying the bubble concentration and/or size distribution, the amount ofscattering may be controlled. For example, a black polymer such as ABSor a black elastomer may be made to look light gray or even white byvirtue of entrapped gas bubbles. Other colors of material than black canalso be used. By controlling the inclusion of such bubbles at a suitablefrequency as the object moves in the direction shown (or the printheadmoves in the opposite direction), an extrudate displaying a variablegray level, preferably ranging from white through black, may be formedusing only black material. An object fabricated with such a capabilitycan thus display gray levels and data on its surfaces, which is useful,for example, in making prototypes of new products. Similarly, an objecthaving variable mechanical properties that are locally specified can beproduced. Since foamed extrudates contain less material and are lighter,and have more surface area, extrudates solidify faster and are lesslikely to sag. Thus, forming a bridging element such as the roof of thecube in FIGS. 55(a) and 55(b) can be achieved even without the use offilament to reinforce the extrudate.

FIG. 72 depicts an isometric view of an extrudate in which is embedded awire that has a 3-D helical form. In some embodiment variations, thewire has a 2-D planar serpentine form (with the shape of the wireanalogous to various waveforms such as sine, triangle, square, andsawtooth waves), or a 3-D, piecewise planar serpentine form (with theplane varying from region to region along the length). While in someembodiments it is desirable to use wire or other filament to provideelectrical conductivity, reinforce polymer, and so forth, incorporatingwire in a form that allows it to stretch may be useful in otherembodiments to minimize the impact on the mechanical properties, such aselongation, of the surrounding polymer, especially if an elastomer.Thus, stretchable, highly-deformable circuits can be made by placingwire having a non-straight shape within an elastomeric material such asTPE; the material may be shaped to follow the wire shape, or may bedifferently shaped, such as the shape shown in FIG. 72. In someembodiments, a mismatch in coefficient of thermal expansion between wireand polymer can be accommodated by shaping it so it isn't straight. Insome embodiments, it is desirable to incorporate a longer length of wireto increase resistance or inductance; depositing the wire in anon-linear form helps with this. In some embodiments, modifying the wireshape as in FIGS. 54(a), 54(b), 54(c), and 54(d) can assist withanchoring the wire within the polymer. In some embodiments, helical orplanar serpentine shapes can help decouple stress from sensitiveelements such as ECPC junctions, sensors whose readings should be freeof parasitic influences, brittle integrated circuits and othercomponents that tolerate little bending, etc. In some embodiments, smallspring-like elements produced as in FIG. 72 are themselves valuable asmechanical elements as springs, flexures, hinges, etc., whethercomprising bare fiber or fiber encapsulated in a matrix; these may bemade in other shapes such as torsional springs, leaf springs, etc. Insome embodiments, wire springs may be produced encapsulated in asacrificial material that aids in forming them; this may later beremoved. Due to the high hardness and springback of typical wire usedfor springs, a nozzle such as that of FIGS. 35-36 may be useful inhelping to bend the wire in some embodiments.

In some embodiment variations, wire may be formed as shown in the figureby moving the capillary tip in a circle perpendicular to the extrusiondirection during the extrusion process, or in the case of planarwaveforms, vibrating it from side to side appropriately. Adjusting theamplitude and frequency of vibration according to the nozzle velocity,polymer solidification rate and viscosity is generally required; forexample, attempting to vibrate with too large an amplitude or too smalla spatial frequency may not work unless nozzle speed is reduced, sincethe wire may simply wiggle within the molten polymer. In some embodimentvariations, merely feeding the wire faster than the polymer may cause itto buckle to form a reasonably-regular serpentine or helical shape. Topromote and control this, vibration with a small amplitude may beimparted to the wire; along with the increased feed rate this caninitiate a controlled bending of the wire into the desired shape, andwith a larger amplitude than the vibration itself.

In some embodiment variations, wire may be pre-formed into such a shapeand incorporated into the extrudate; for example, wire having a helicalshape can be delivered by a capillary that is similarly shaped, byrotating the wire. 2-D and 3-D patterns may be imposed on the wire insome embodiments by embossing the wire in its manufacturing process, ordoing so as it is being dispensed and fed into the fabricated object.

FIG. 73 is an isometric view of a capacitor (which may be used as apressure, force, or displacement sensor) produced in some embodimentsusing wire embedded at least partially in a dielectric (not shown) suchas a thermoplastic. The upper and lower plates of the capacitor, as wellas the leads, are produced by wire (e.g., having a square cross sectionas shown) which is wound to form the plates. The wire may besubstantially bare, or may be coated with polymer. For example, if thewire is delivered by an external capillary such as that of FIGS. 30(a),30(b), and 30(c) and the fabricated object is attached to a buildplatform that is rotated as in FIG. 42, then winding may be accomplishedby anchoring the wire end at the center of the plate (e.g., with a smallvolume of polymer) and rotating/translating the stages appropriately.The space between the plates may be left substantially empty; however,filling it with polymer to increase dielectric constant—and in someembodiment variations, a polymer with an enhanced dielectric constant(e.g., containing particulate)—may be desirable. In other embodimentvariations, capacitor plates are produced using ECPC within which wireis embedded (e.g., toward one edge, across a diameter, or in a loosespiral).

FIG. 74 depicts an isometric view of a spiral inductor produced in someembodiments using wire embedded at least partially in a dielectric. Thewire may be bare and may be square in cross section, and may bedeposited in a loose spiral on top of polymer, to which it can anchor(e.g., the wire may be pre-heated), or the wire may be deposited alongwith polymer, forming an insulating coating. Leading into the coil onthe top layer is the upper lead. Above or below the inductor a region ofECPC is provided, connecting the inner end of the coil to the lowerlead, which may be at least two layers below the upper lead.

FIG. 75 is a plan view (or an elevation view) showing a resistorproduced in some embodiments. Three adjacent extrudates are shown. Thecenter extrudate comprises pure polymer and ECPC, while the outerextrudates are pure, insulating polymer. Wires leading into and out ofthe ECPC region are also provided. The value of the resistor may becontrolled by any or all of various parameters such as thecross-sectional area of the ECPC, the length of the ECPC, the distancebetween the ends of wires in the ECPC, and the ECPC conductivity, whichmay be varied for example by varying the conductive fillerconcentration. In some embodiments, resistors with non-linear shapes maybe produced, such as serpentine and helical resistors.

FIGS. 76(a), 76(b), 76(c), and 76(d) depict cross-sectional elevationviews of extrudates according to some embodiments, in which the embeddedwire or other filament is intentionally not coaxial with the polymer;i.e., the wire is offset to the side as in FIG. 76(a) or top as in FIG.76(b), for example. In FIG. 76(c), extrudates with wires offset to thesides are shown forming a shaft and plain bearing. The wires that arepart of the extrudates on the surface of the shaft are offset toward theoutside diameter of the shaft. Meanwhile, the wires that are part of theextrudates on the inside of the hole in which the shaft turns are offsettoward the inner diameter of the hole. Together, these offset wires formbearing surfaces. In some embodiments, these bearing surfaces may bemachined using a subtractive operation such as drilling (for the plainbearing) or turning, in order to achieve more exact tolerances and/orbetter surface finishes. In some embodiment variations, the wires usedfor the shaft and plain bearing are hard materials and/or materialscontaining particles of PTFE, bronze, etc. to provide lubricity and wearresistance. To maximum contact area, wire with a rectangular crosssection can be used. In FIG. 76(d), by contrast, the wires are offset tothe bottom of the extrudate, for example, so as to provide pads ontowhich an integrated circuit die can be bonded, e.g., using solder bumpsor a conductive adhesive. Other reasons for locating filament off-centerinclude reducing or increasing spacing to change capacitance or allowhigher voltages without arcing, and allowing direct contact betweenwires in bare regions (e.g., for a pressure-actuated switch).

FIGS. 77(a), 77(b), 77(c), and 77(d) depict nozzles used in magneticextrusion and extrudates produced, according to some embodiments. FIG.77(a) depicts a nozzle in plan view composed of ferromagnetic materialsuch as nickel or steel. In FIG. 77(b), the nozzle is surrounded by aradially polarized, ring-shaped permanent magnet (e.g., as provided byMagma Magnetic Technologies of Israel) or electromagnet, or a ring ofindividual permanent magnets or electromagnets aligned so that all theirSouth (or North) poles are pointed inwards, a ring-shaped ferromagneticmaterial interfaced to a magnet pole; a rapidly-spinning magnet ormagnets, etc. In any of these cases, the intent is to create a radialmagnetic field whose flux passes through the nozzle, and which can causemagnetic particles within the orifice to be drawn outwards, toward theinner diameter of the nozzle (i.e., orifice edges). Polymer in which aferromagnetic powder such as silver-coated nickel or iron is dispersedcan be extruded through a nozzle such as that of FIG. 77(b) and a wireembedded it. If the magnetic field is turned off (e.g., by pulling thepermanent magnets out of contact with the nozzle, or turning off theelectromagnet(s), and if a wire is provided, the nozzle can deposit aextrudate similar to that shown in the cross-sectional view of FIG.77(c), in which the powder particles are substantially disperseduniformly. If the particle concentration is below the percolationthreshold, then the extrudate is not conductive, other than through thewire, though in some embodiment variations, the extrudate may beconductive. However, if the field is turned on, particles may be drawnto the inner diameter of the nozzle and remain near the surface of theextrudate. The resulting increased concentration at the surface cancause percolation, making the extrudate conductive at its surface andremaining dielectric in its interior. In this case, in conjunction withthe wire, the extrudate forms a coaxial conductor that may be suitablefor high-frequency signal propagation, or can serve as amulti-directional pressure, force, or touch sensor. In some embodimentvariations, no wire is provided, but the extrudate may be made locallyeither conductive or insulating, depending on whether a magnetic fieldis applied to the nozzle at the moment of extrusion. Though theconductivity thus obtained is low compared with extrudates which includewires, the ability to switch on and off conductivity in a singlematerial can be useful and is relatively simple. In some embodimentvariations, a radial magnetic field may be used to modify thepercolation behavior of an extrudate containing ferromagnetic particles.For example, if the extrudate is more conductive axially than radially,then the field may be used to help redistribute and/or chain theparticles to obtain a more isotropic conductivity. In lieu of usingferromagnetic particles and a magnetic field, similar behavior can beobtained using dielectric particles and an electric field, causingparticles to migrate by electrophoresis.

In some embodiments, it is desirable to move the particles in order toalter material properties or create a visual effect. For example, anextrudate composed of white polymer mixed with dark ferromagneticparticles may appear white or light gray normally, but can be made toappear dark on its surface by applying a magnetic field to attract theparticles to the surface while the polymer is molten. When the polymersolidifies, the particles are locked into their new positions. In thisway, gray-scale surface coloration can be obtained in a fabricatedobject. Preferably the entire perimeter of the extrudate is colored,since any portion of the surface may be exposed to the outside of thefabricated object, depending on whether the extrudate is forming part ofa vertical surface, an top/up-facing surface, a bottom/down-facingsurface, etc.

In some embodiments, high speed rotation of the nozzle may be used tocause particles dispersed in the polymer, especially if considerablydenser than the polymer, to be brought near the surface of the extrudateby centrifugal force, where they may percolate to form conductive paths,modify material properties, or cause coloration differences and visualeffects.

FIGS. 78(a) and 78(b) depict cross-sectional elevation views of aprinthead “hot end” similar to that of FIGS. 2, 7(a), and 7(b), andwhich may be used in some embodiments with an external capillary such asthat of FIGS. 30(a), 30(b), and 30(c). As is the case with many figuresin this application, the figure is not to scale; in particular, thediameter of the filaments is normally larger than that of the orifice.In FIG. 78(a), the hot end is shown with two filaments (e.g., pureelastomer and elastomer-based ECPC), each entering a flow channel. It isassumed that the entire hot end shown is heated to liquefy thefilaments. Both flow channels lead to a central chamber whichcommunicates with the orifice of a nozzle. To more easily manufacturethe flow channels, holes may be drilled from the outside for theirhorizontal runs; these are then plugged. The roof of the chamber is atightly-fitting plunger, shown raised in FIG. 78(a), and lowered in FIG.78(b). As the lower region of the chamber is tapered (e.g., conical),which is desirable in some embodiment variations, the lower portion ofthe plunger is shaped to conform to the chamber shape such that bylowering the plunger the volume of material in the chamber can becompletely exhausted through the nozzle, purging the chamber. In use,filament 1 may be fed (e.g., by rollers) into its flow channel, withmolten material 1 filling the channel and chamber while the plunger israised (FIG. 78(a)) and extruding from the nozzle. In preparation forswitching to the material 2, the plunger is lowered as in FIG. 78(b),purging the remaining material 1. During the purge, filament 1 is nolonger advanced into the hot end, and the plunger motion may be adjustedto produce the same flow rate that previously was obtained by advancingfilament 1. The plunger is then raised again and filament 2 fed into thehot end, filling the chamber with material 2 and extruding it from thenozzle. In preparation for changing back to material 1, the plunger islowered again at a controlled rate until material 2 is purged, and soforth.

FIGS. 79(a) and 79(b) depict in cross-sectional elevation views a methodused in some embodiments for decoupling stress from ECPC-based junctionsbetween wires, which may be useful, for example, when using ECPC havinga conductivity that is particularly sensitive to strain. The junctionshown is between two wires on two adjacent layers: layers N and N+1.Each wire exits dielectric material surrounding the junction region,passes through air (or sacrificial support material), and enters aregion of ECPC. In the figure, the wires both terminate within suchregions, though that is not necessarily the case. In the figure, thewires enter their ECPC regions from opposite sides, though that is notnecessarily the case. In the geometry shown, the ECPC for layer N isdeposited onto a removable (e.g., soluble) support material on layer N−1as shown in FIG. 79(a). After removal of the support material as in FIG.79(b), the ECPC junction is suspended within a cavity in the surroundingmaterial by only the wires. In this way, stress applied to thesurrounding material is largely decoupled from the ECPC, resulting in amore consistent and reliable junction. In some embodiment variations,the geometry is modified such that no temporary support material isrequired to achieve useful isolation. In some embodiments, the junctionis protected by use of stiffer material in its vicinity, for example,fully-encapsulated stiff support material, or deposited dielectricpolymer with a high elastic modulus. Since abrupt transitions in elasticmodulus between ECPC and surrounding material may in some casesexacerbate stresses in ECPC, graded, transition materials may be used.

In some embodiments, electrical robustness of the fabricated object canbe improved by providing redundancy in electrical junctions betweenwires, such that stresses which may compromise the performance of one ormore junctions may still leave other junctions fully functional.Redundant junctions, as they are electrically in parallel, can providereduced overall resistance even in situations where junction performanceunder stress is not an issue.

In some embodiments, the extrudate may be rapidly solidified (orsignificantly increased in viscosity due to a drop in temperature,hereinafter “solidified”) upon exiting the nozzle, for example, throughthe application of a flowing cooling gas to the extrudate. Such “rapidsolidification” can serve several purposes. One is to “lock” the wire inplace, anchoring it so it can be pulled out of the capillary forfeeding, and immobilizing it so as to minimize any tendency for it tocome out of the extrudate, for example, when the nozzle follows atoolpath with turns of small radius and/or when the nozzle is movingrapidly along the toolpath. Another purpose—even when no embedded wireor other filament or fiber is involved—is to reduce and sometimeseliminate the need for supports in the fabricated object, by giving theextrudate enough mechanical strength to not sag or collapse of its ownweight when poorly supported, or not supported, by the structure below.For example, in FIG. 55(b), rapid solidification can be used to helpform the top of the cube, even if no wire is provided. Similarly, rapidsolidification can enable geometries such as walls at large (e.g., >45°)angles to the vertical and cantilevers such as those shown in the planview of FIG. 80(a), unsupported rings such as that shown in the 3-D viewof FIG. 80(b), etc. Indeed, while it is sometimes possible to extrudematerial rapidly to form a straight, unsupported span due to cohesiveforces in the material providing a tensile stress in the extrudate, itis not normally possible to create a structure such as that of FIG.80(b) without supports unless rapid solidification is used. In the caseof materials such as metals which form grains upon solidification from amolten state, rapid solidification can be used to produce a finer grainstructure than would normally be achieved. In the case of metals andother materials (e.g., waxes) having low viscosities and/or high surfacetensions which one wishes to extrude in an AM process, rapidsolidification can quickly mechanically stabilize and harden the moltenmaterial, making controlled, precise deposition possible.

Rapid solidification of extruded material can be accomplished by asignificant flow of a cooling fluid, such as air, whether at ambienttemperature or cooler than ambient. Other gases, as well as liquids maybe used in some embodiments, as can liquids (e.g., delivered as a finemist) which preferably evaporate, also cooling the extrudate by removingthe heat of vaporization. Small fans mounted to the printhead which canprovide airflow to the printed layer are sometimes used in FDM systems.Diffuse, non-localized cooling such as by a fan may help in rapidsolidification if the flow rates are high. In some embodiments,localized, focused cooling of the extrudate using a fluid at ambienttemperature or below ambient temperature can be used instead, typicallyto far greater effect. FIGS. 81(a), 81(b), and 81(c) depictcross-sectional elevation views of apparatus for rapid solidification asused in some embodiments. In FIG. 81(a), a downward-pointing coolingtube, or conduit, (or more generally, a tube pointing toward theextrudate, which is typically below the nozzle), is provided as part ofthe printhead, adjacent to and “downstream” of the nozzle (i.e., in thenozzle's “wake”), such that material extruded by the nozzle arrivesbeneath the tube when the nozzle is moved in the direction shown (orequivalently, when the fabricated object/build platform is moved belowthe nozzle). Though not shown in FIGS. 81(a), 81(b), and 81(c), if acapillary is provided to deliver fiber for encapsulation (as in FIG.29(a), 29(b), or 140), the capillary typically is located diametricallyopposite the tube on the other side of the nozzle (i.e., on the leftside in the figure), such that as the nozzle moves along the toolpath,the capillary leads the nozzle, and the cooling tube follows it, withboth rotating as necessary relative to the fabricated object, to followthe path.

Through the cooling tube passes gas (e.g., air) which in some embodimentvariations is at the same temperature as the room or chamber in whichthe object is fabricated, while in other embodiment variations may bechilled (e.g., by a thermoelectric cooler, or passing a hose conductingthe gas through an acetone and dry ice bath, or using a compressed aircooler such as the CHILLYBITS™ cold air blaster from Abanaki Corporation(Chagrin Falls, Ohio). Chilling the gas can maximize the rate ofsolidification while minimizing the velocity and flow rate of the gas,since excessive gas kinetic energy may tend to deflect the extrudateaway from the tube. The gas emerging from the tip of the tube impingeson the extrudate, rapidly solidifying it. In FIG. 81(b), a similar tubeis provided, but at an angle that permits the gas to impinge upon theextrudate even sooner after the latter has been extruded, thus coolingand solidifying it even faster. The shape of the tube or the tip throughwhich gas exits may be circular, elliptical, rectangular, square,slot-shaped, or have another geometry which optimizes cooling anddirects the flow as desired. Since hot air surrounding the extrusionnozzle may be entrained by the gas issuing from the cooling tube,warming it, in some embodiments the nozzle and/or the tube is insulated.Methods of insulation include coating the nozzle exterior (e.g., on theside nearest the tube) and/or tube with an insulating paint such as thatmade by Hy-Tech (Melbourne, Fla.), covering it (e.g., with a cap) with athermally-stable, low thermal conductivity material (e.g., a cap) suchas ceramic, fiberglass, glass, silicone, PEEK, or aerogel. In someembodiments, the nozzle may be insulated by these methods merely tobetter maintain the correct temperature.

In some embodiments a shield may be used between the nozzle and coolingtube to prevent inter-mixing of the cooling air and air heated by thenozzle; in some embodiment variations the shield may surround thenozzle, while in other embodiment variations it may be located primarilyin the region between the nozzle and cooling tube. In some embodiments,a thermoelectric device may be used adjacent to the nozzle to avoidoverheating the air near the cooling tube. In some embodiments, theReynolds number of the flow from the cooling tube is adjusted so as tominimize mixing with and entraining hot air adjacent to the nozzle.

In the case of the apparatus of FIGS. 81(a) and 81(b), the tube may insome embodiments rotate around the nozzle axis such that the tuberemains substantially downstream of the nozzle regardless of thetoolpath along which the nozzle moves (e.g., the line between nozzleaxis and tube tip remaining tangent to the toothpath). The object mayrotate about an axis substantially coincident with the nozzle (e.g.,using apparatus as in FIG. 42) to achieve a similar effect.Alternatively, the printhead shown in the cross-sectional elevation ofFIG. 81(c) comprises a ring-shaped manifold which surrounds the nozzle,provided with a slot at or near its bottom through which gas may impingeon the extrudate no matter what the orientation of the extrudate inorder to rapidly solidify it. In other words, the manifold of FIG. 81(c)acts as an omnidirectional cooling manifold; one that requires nomechanical rotation of a cooling tube or the fabricated object, and isthus easily adapted for use in standard FDM-type machines to provide,for example, the ability to fabricate parts using far fewer—or in somecases no—supports.

In some embodiments, gas flow rate, gas temperature or type, and/orcooling tube position may be adjusted during the fabrication processaccording to varying needs, e.g., based on the geometry of thefabricated object. For example, while extrudates comprising the firstlayer of a cantilever such as that of FIG. 80(a) might requiresignificant acceleration of solidification to allow accuratefabrication, extrudates comprising subsequent layers of the cantilevermay require less or no acceleration. Moreover, excessive cooling of anextrudate intended to fuse with or adhere to material on the layer belowit, or material adjacent to it on the current layer, may be impaired byimproper or excessive cooling and solidification. Thus, for example,while the gas stream may be adjusted (e.g., by a flow controller,proportional valve, or pressure regulator controlled by the controlsystem) to provide significant flow when printing the first layer of thecantilever in FIG. 80(a), the flow may be much reduced for subsequentlayers.

FIGS. 82(a) and 82(b) depict elevation views of a printhead from anangle parallel to the long axis of several extrudates (i.e., theprinthead or printed object move normal to the plane of the figure). Inboth figures, a wall comprised of extrudates such as those shown hasbeen fabricated, at an angle beta to the layer plane. As shown, thetamight be ordinarily too small to be practical without the need forsupports, or it may be an angle that is practical for extrudate byitself, but not for a composite extrudate that includes wire. Whilebenefiting from rapid solidification, the extrudates nonetheless need tofuse with the extrudates beneath them and to their sides.

In FIG. 82(a), a cooling tube is provided which blows in a directedfashion on the extrudates so as to preferentially rapidly solidify theportion of the extrudates that is not overlapping or adjacent to othermaterial, thus providing the benefits of rapid solidification withoutsignificantly compromising adhesion of the extrudates to other material.In some embodiments the tube may be entirely above the lower extremityof the extrusion nozzle, while in other embodiments it may be below asshown. When below, it may be retractable, or it may be re-positionableso as not to collide with previously-deposited material (e.g., it mayrotate about the nozzle axis). FIG. 82(b) depicts a similar arrangementbut one in which a tube producing a narrow stream or jet of gas ispositioned downstream of the nozzle but offset to one side of the nozzleaxis so as to preferentially rapidly solidify material not adjacent topreviously-deposited material. The offset may be adjustable (e.g., usinga positioning actuator) depending on geometry; for example, whendepositing extrudates comprising a wall leaning to the right (vs. to theleft, as shown), the cooling tube may be offset to the right of thenozzle axis, (vs. to the left as shown).

In some embodiments the cooling tube may be designed to produce a narrowstream or jet of gas that impinges on the center of the extrudate, suchthat part of the extrudate is rapidly solidified, but part remainsmolten long enough to fuse with underlying material and with material onat least one side of the extrudate on the same layer. If the latter isnot a requirement, alternatively the gas may impinge on both sides butnot the center of the extrudate to achieve good adhesion with theunderlying layer.

FIG. 83 depicts an arrangement similar to that of FIG. 44, to which hasbeen added a cooling tube downstream of the nozzle. The tube may befixed to the plate such that, along with the capillary, it rotates withthe plate according to the local direction of printhead motion along thetoolpath. Cooling tubes and manifolds such as those shown in FIGS.81(a), 81(b), 81(c), 82(a), 82(b), and 83 are preferably designed sothat the flow of gas minimally impinges on the nozzle, which risksexcessively cooling the nozzle and slowing or preventing extrusion. Insome embodiments, the nozzle can be shielded and/or at least partiallymade from a material which has low thermal conductivity to mitigatethis. Also, in some embodiments, the tube or manifold is designed (andpossibly shielded) to minimize entrainment of warm air surrounding thenozzle by the flowing gas, which can increase the gas temperature.

In some embodiments, however, cooling of the nozzle may be usedintentionally as a means of modulating flow from the nozzle. Forexample, when the printhead makes a discontinuous jump between locationson a layer, if the flow is not stopped or even reversed as is thepractice typically with FDM, an undesirable “stringer” of extrudedmaterial will typically result. Cooling of the nozzle using an impinginggas stream, a flow of liquid onto or through channels in the nozzle,etc. can be useful to abruptly stop the flow of material and avoidstringers (conversely, intermittent or periodic heating of the nozzleusing an impinging stream of heated gas can temporarily increase flow,providing a rapid modulation of the extrudate width which be used toadvantage to create surface textures, etc.)

In some embodiments, rather than, or in combination with, blowing gasonto the extrudate to rapidly solidify it, air may be made to impingeonto the extrudate by drawing it into a tube in proximity to theextrudate; this upwards-directed airflow can also help to offset theforce of gravity acting on the extrudate to make it sag and/or the forceof a gas jet impinging on the extrudate from above. In some embodiments,a vacuum nozzle designed to reduce air pressure above the extrudate butnot draw in any partially-molten material may be located downstream ofthe nozzle to support the extrudate as it hardens.

In some embodiments, the extrudate may be cooled to promote rapidsolidification by using a liquid that impinges on the extrudate, such asa fine mist of water or alcohol that quickly evaporates. In someembodiments, the extrudate may be cooled by direct contact with anelement (e.g., a plate, a ring surrounding the nozzle allowingomnidirectional nozzle motion) which has high thermal conductivity(e.g., made from aluminum) and/or high heat capacity, and which in someembodiment variations may be actively cooled. The element may be madefrom or coated with a material such as PTFE to minimize adhesion of theextrudate.

In some embodiments, more than a single cooling tube or manifold may beused. For example, two tubes may be used with different locations and/orangles such that the flow impinging on the extrudate is more balancedand the net force on the extrudate reduced, than would be the case witha single tube that is asymmetric. The tube shown in FIG. 82(a) on theleft of the nozzle may be replicated symmetrically on the right and bothtubes may be higher so as not to be below the nozzle tip and interferewith the previously-deposited material.

In some embodiments, fillers may be added to the extruded material toincrease thermal conductivity and/or reduce the volume fraction ofmolten material, thus promoting rapid solidification. For example, fineboron nitride powder may be used to increase thermal conductivity ofsome polymers, while hollow glass microspheres or particles of athermoset polymer may be used to reduce the molten polymer volumefraction. In some embodiments, thermally-conductive polymers such asCoolPoly® D8102, made by Celanese (Irving, Tex.) may be used.

In some embodiments in which the extrudate is deposited onto underlyingmaterial, it may be cooled from its top surface so as to solidifymaterial at or near that surface before the remainder of the extrudatevolume. When the remaining of the volume solidifies and shrinks,shrinkage-related stresses associated with contact with the underlying,already-shrunk material, can thus be more balanced than is normal inFDM, reducing the tendency to curl the layer.

Commercially available FDM filaments typically do not have durometersbelow 70 or 75 Shore A, comparable to those pursued in the past [Elkins,1997; Stratasys' E20]. The extrusion of softer (lower durometer and/orlower modulus of elasticity) materials such as Chronoprene with adurometer of 5 Shore A or even Kraton D1162P (with a durometer of 53Shore A) using a conventional FDM-type printhead is currently notpossible due to buckling of the filament en route to the hotend/liquifier when fed by rollers or gears, and/or poor traction on thefilament by the rollers or gears, allowing slippage. Therefore, in someembodiments, a printhead/extruder of a design similar to that shown inthe cross-sectional view of FIG. 84 may be used. The printhead comprisestwo relatively thin (i.e., in the direction perpendicular to the drawingsheet) rotating elements, which may have the form of blades as shown(e.g., slitting cutters/saws), but which in some embodiments have theform of thin gears, thin rollers (e.g., with hard or elastomericsurfaces), spiked wheels such as the pounce wheel-like structure ofFIGS. 70(a), 70(b), and 70(c), etc. (hereinafter “blades”). The bladesare spaced so that the gap (the “blade gap”) between their outsidediameters is smaller than the diameter of the filament to be fed. Theblades are driven to counter-rotate as shown, such that the bladerotation forces the filament toward the heated “hot end” of theprinthead, including the extrusion nozzle (i.e., “downstream”).Surrounding and guiding the filament is a tube similar to the liquifiertube or barrel screw of conventional FDM printheads, but with a keydifference: the tube is slotted as shown in FIG. 85, such that bladescan engage the filament much further downstream than the gears orrollers of a conventional FDM printhead, located upstream of theliquifier tube/barrel screw, can engage the filament. Use of a slottedtube and thin blades enables the location at which force is applied tothe filament to be much further downstream, with the critical resultthat the filament is pulled through the tube for at least a significantpart of its travel, rather than being pushed through as in the priorart. Pulling avoids buckling of filaments that are soft and/or lowmodulus, allowing them to be efficiently driven into the hot end, wherethey can be fully liquified and extruded. Meanwhile, the blade gap canbe set to be small enough that the blades penetrate the filament enoughto grip it securely, without slippage. In some embodiments the extrusionaxis of the nozzle is parallel to the filament and filament feeddirection, as in FIG. 84. In other embodiments, the extrusion axis is atanother angle to the filament/feed direction, such as 90 degrees as inFIG. 85. The design of the hot end block is of course somewhat differentfor these two embodiments.

The inside diameter of the tube may be somewhat smaller than the outsidediameter of the filament, as shown, or the two dimensions may be closeto one another. In some embodiments, filament with non-circularcross-section may be used (e.g., to increase the contact area with theblades or other driving elements. For example, filament may have asquare cross section. Softening of the filament may begin in the tube(e.g., in the downstream portion of the tube as shown), or may not occursignificantly until further downstream, e.g., where the tube is embeddedin the hot end (however in some embodiments the tube and hot end form asingle piece). In some embodiments the upstream portion of the tubeand/or the filament is cooled by a manifold (as shown in the 3-D viewsof FIGS. 85-86) through which cooling gas such as compressed air ispassed, so as to avoid premature softening of the filament. Soft tubingmay be connected to the upstream end of each manifold. The flow from themanifolds should preferably not impinge on the hot end, which may reduceits temperature. In FIG. 86, an alternative design of the manifold isshown on the left, in which the flow is directed more upstream and awayfrom the hot end than in the right-hand design. FIG. 87 is a photographdepicting a slotted tube (which may be externally threaded in someembodiments), two rotating blades mounted to mandrels, and a filamentbeing fed by the blades rotating as shown through the tube in thedirection shown.

The blades are preferably located as far downstream as possible, but notso far as to engage the filament in a region where it has begun tosoften significantly. In some embodiments, the blades are smaller thanshown so that they may be located further downstream. In FIG. 84 it willbe noted that the downstream end of the slot may be cut at an angle(e.g., using a slitting saw) so that the tube conforms better to theblade and any solid or semi-solid material that may be separated fromthe filament by the blades cannot readily escape the tube in the smallgap (the “blade-tube gap”) between it and the blades, and is insteaddriven into the hot end. FIG. 85 depicts the hot end block and slottedtube mounted to a slide used in some embodiments which can move in thedirections shown to adjust the blade-tube gap. The thickness of theblades is preferably close to that of the tube slot, to minimize escapeof material between the blades and the tube. In some embodiments, meansof collecting and/or recirculating material that does escape from thetube are provided. In some embodiments, the blade-tube gap is mostlyclosed by means of a flexure (e.g., steel) or other compliant element oneach side of the tube, adjacent to the blade. In some embodimentvariations, to accommodate a flexure and allow for reverse operation toretract the filament, the blade teeth may be more symmetric (e.g.,triangular) than shown in FIG. 87, or smaller, or blunt/rounded, or noteeth may be used at all (e.g., the “blades” may rely on frictionalone), the latter allowing the blade-tube gap to be made extremelysmall.

As will be noted in FIGS. 84 and 87, if the blades include saw-liketeeth, then in some embodiments they may be reversed in orientation whencompared with the orientation used for normal sawing/slittingoperations: i.e., the sharp tip of each tooth may point upstream ratherthan downstream. As shown in FIG. 85, the blades are supported onmandrels which allow them to rotate freely. The mandrels may besupported by bearings (not shown) within the base plate which supportsmuch of the assembly. Not shown in FIG. 88 and other figures are aheater (e.g., a cartridge heater) and temperature sensor (e.g., athermistor or thermocouple) for the hot end block. The slide ispreferably made of material of low thermal conductivity (e.g., ceramic,steel) so that the hot end block can be heated efficiently; in someembodiments the block may be mounted to the slide using only the tubeand possibly one or more spacer, the intent being to reduce contactsurface area and thus heat transfer.

As illustrated in the 3-D view of FIG. 88, the mandrels are driven bygears which are meshed so as to counter-rotate when one mandrel isturned by means of a driven pulley. The driven pulley is turned by abelt (the path of which is shown in outline in this and other figures)connected to a driving pulley turned by a motor. To feed material, theblades are rotated in the direction shown in FIG. 87. As with a standardFDM printhead, reversing the blade rotation can be used to withdraw thefilament and to retract the extrudate or prevent seepage of moltenmaterial from the nozzle, e.g., to avoid stringers.

In some embodiments, the blade gap may be adjusted (e.g., byincorporating a compliant element in the base plate holding themandrels) to accommodate different mechanical properties (e.g.,hardness) and/or cross-sectional dimensions of filament, and in someembodiments the blades may be spring-loaded against the filament, e.g.,with an adjustable force. In cases where the blade gap may be varied,both blades may be driven by belts instead of by gears, to avoidsub-optimal gear tooth engagement. In some embodiments the tube is madefrom a low-friction material such as PTFE, or is lined with such amaterial (e.g., coated with PTFE or AMC148-18).

FIGS. 89-92 depict 3-D views the assembly of FIG. 88 in which the baseplate is mounted to a flexible printhead support plate used in someembodiments. In some embodiments the support plate is shown mounted to aZ stage plate, which is mounted to the Z stage carriage. Between the Zstage plate and support plate in some embodiments is a stage whichallows adjustment of the nozzle position along the X axis as shown inFIG. 89. Meanwhile, as shown in FIG. 90, the support plate can be flexedslightly by tightening or loosening the Y axis adjusting screw to movethe nozzle along the Y axis. Such adjustments are useful when aligningthe nozzle orifice to be coaxial with the axis of the theta stage ofFIG. 42. FIG. 92 provides a useful closeup of the slide, which can movein the direction shown by sliding along guide pins within a slot in theslide.

FIG. 93 depicts a cross-sectional view of an extruder similar in somerespects to that shown in FIG. 84. However, in lieu of rotating bladestwo grippers are provided to feed the filament. The grippers can in someembodiment variations be provided with teeth such as thedownstream-pointing saw-like teeth shown. In such embodiments thegrippers may move in a linear reciprocating motion as shown on theright-hand gripper, pushing filament downstream with each downstreamstroke, and with the return (i.e., upstream) stroke slipping on thefilament due to the asymmetrical shape of the teeth. In other embodimentvariations, the grippers are not provided with teeth, or may be providedwith more symmetric teeth, and the gripper motion may be more ellipticalor racetrack-shaped: with the gripper closer to the filament during thedownstream portion of the stroke, and then further from the filament (soas to not grip it) during the upstream portion of the stroke.

In some embodiments in which wire is embedded into a reflowable/meltablematerial (e.g., a thermoplastic), as already described for example inconnection with FIGS. 13(a), 13(b), and 13(c), the material may bemelted or softened prior to embedding the wire through the applicationof heat or ultrasonic energy. For example, a heat source that precedesan embedding device that embeds the wire (such as a roller) can be used.The heat source may be a laser, an infrared source, a stream or jet ofheated gas (e.g., air), etc. FIG. 94 depicts in a cross-sectionalelevation view a wire embedding head in which an embedding device (e.g.,a roller) presses wire into the surface of a thermoplastic object (e.g.,one of more layers fabricated using FDM, selective laser sintering, oran injection-molded part). Ahead of the roller, heating a region of thepolymer, is positioned a tube through which heated air is passed suchthat the air impinges on the polymer and softens or melts it, allowingthe roller to press the wire into the surface. In some embodiments, theheated air itself does not sufficiently heat the polymer, but rather, itpre-heats it and the wire is separately heated (e.g., Joule heated,using electrical contacts on the roller, brushes rubbing against thewire at different locations, etc.) by the additional amount required forembedding, or the wire is ultrasonically vibrated (e.g., by the rollerserving as a sonotrode). The roller may rotate relative to thefabricated object around an axis perpendicular to the layer (i.e.,vertical) or parallel to the local surface normal, or vice-versa.

In some embodiments as shown in FIG. 94, a tube through which gas (insome embodiment variations, chilled gas) is delivered is provided in thewake of the wire embedding device (e.g., a rotating or non-rotatingroller) to rapidly solidify the thermoplastic after the wire has beenembedded. Such rapid solidification can allow for smaller radiusturns/bends of the wire, for example, and reduce the risk of the wiremigrating or being pulled out of its intended position (e.g., by tensionon the wire). It can also be useful for quickly anchoring the end of thewire, e.g., to allow it to be pulled into the embedding device undercontrolled tension as the wire embedding head advances.

In some embodiments, both a means of heating the polymer ahead of theembedding device and a means of cooling the polymer in the wake of theembedding device is provided, as in FIG. 94, where two tubes areprovided. Since the direction of the wire may vary considerably as atoolpath for embedding is followed during the embedding process, thetubes and embedding device may be arranged to rotate (around an axisperpendicular to the object surface, or if the surface is not a planarlayer, then parallel to the local surface normal) relative to thethermoplastic object, or vice-versa. In some embodiments, an embeddingdevice other than a roller may be used, such as a plate (e.g., a plateor “ski” having a rounded leading edge). In some embodiments, the rollermay be of the form of the wheel shown in the 3-D view of FIG. 95(a), orthe wheel shown in FIGS. 70(a), 70(b), and 70(c), a variant of which isshown in the 3-D view of FIG. 95(b). In FIG. 95(a) the wheel is providedwith a bore in some embodiments to allow rotation around a shaft (notshown) and in some embodiments with a groove in its central portion toaccept wire and keep it centered and in a controlled position on thewheel. The central portion of the wheel is preferably as narrow aspossible, to not interfere with embedding wire well below the surface ofthe thermoplastic substrate, either in the topmost layer or in a layerbelow the topmost layer. The wheel may rotate in some embodimentvariations, or simply slide, serving as a guide. In some embodimentvariations, the wheel may be provided with at least one shoulder whichcan slide or roll upon the surface, controlling the depth of the wire(acting as a stop) and in some embodiment variations facilitating orcausing rotation of the wheel as it moves, through contact with thesubstrate. In some embodiments the depth of embedding is determined notby contact between the shoulder and the substrate surface, but byadjusting the height of the wheel (e.g., by raising and lowering a shafton which the wheel turns), thus allowing the wire to be embedded at adesired, programmed depth.

As the wheel moves forward, wire is fed toward the substrate. The wireis not necessarily perpendicular to the substrate as it feeds into thewheel as shown in FIGS. 95(a) and 95(b), and may be introduced at a muchsmaller angle to the substrate surface (e.g., to minimize residualstress and/or fracture or other damage to the wire). In some embodimentsrotation of the wheel may be measured and used to feed the wire at thecorrect speed. FIG. 95(b) depicts a 3-D view of a wheel similar to thatof FIG. 95(a), but with slots around its periphery. Such slots can beuseful to allow polymer to better envelope and capture the wire duringthe embedding process. Wheels as well as other shapes of embeddingdevice, designed with specific groove shape, groove depth, number ofgrooves (e.g., a wheel with multiple grooves to accommodate multiplewires), slot size and shape, etc. may be used in various embodiments.Wires that are rectangular or square can be accommodated bysuitably-designed grooves. For example, wires that are rectangular canbe embedded with the wider dimension perpendicular or parallel to thesubstrate surface. In some embodiments, the wheel may be designed as acam (e.g., a spiral cam) and the groove radius may vary with rotationangle. Such a wheel, rotating as needed to select a different radius,but not rolling, can serve as a variable-depth wire embedding device.

FIGS. 96(a), 96(b), 96(c), 96(d), 96(e), and 96(f) depict in across-sectional elevation view an alternative approach to embedding wirethrough the use of wire heating and/or vibration. In FIG. 96(a), alayered object fabricated from (dielectric) thermoplastic using AM suchas FDM is shown; however, the method may be used for monolithic objectsuch as those which are molded. Cavities (e.g., cylindrical) areprovided on either side of a region in which it is desired to embedwire, these can also serve to hold a conductive material used to form ajunction, for example. In FIG. 96(b), wire held taut between two clampsis introduced above the topmost layer. The wire is then heated (e.g., bypassing an electric current through the wire with the two clamps servingas electrodes) and in FIG. 96(c) has been plunged into the thermoplasticmaterial on the topmost layer; in some embodiments the cavities may bedeeper and the wire plunged further into the object, e.g., severallayers below the topmost layer. In some embodiments, the wire may bethicker than a single layer thickness, and may therefore span more thanone layer. The wire is then allowed to cool and the clamps are releasedand withdrawn, as in FIG. 96(d). In FIG. 96(e), the process has beenrepeated on another layer, and in FIG. 96(f), a conductive material(e.g., solder, solder paste, solder with particulate filler (e.g., metalor metal-coated particles), ECPC, conductive epoxy, conductive ink) hasbeen added to one end of two adjacent wires to form a junction, ifrequired. The material may fill the cavity or as shown, only contact thewires and in some cases be supported by them, without contact with thewalls of the cavity.

In some embodiments, the conductive material may be deposited in thecavity prior to introduction of the wire; in such cases the heated wirecan not only melt the dielectric material, but also melt and/or reflowthe conductive material in the junction, if desired. In someembodiments, using embedding approaches such as those of FIGS. 94,95(a), and 95(b) which heat the wire or vibrate it ultrasonically, thewire may similarly be embedded into conductive materials already presentin the substrate, as well as and in some embodiment variations in thesame operation as embedding it into dielectric materials.

In some embodiments, rather than heating the wire to allow it topenetrate, or as an adjunct to heating it, the wire may be vibrated(e.g. at ultrasonic frequencies) using the clamps, for example along itslong axis or transverse to that axis. In some embodiments, no cavitiesare provided initially, but the clamps are able to penetrate thematerial of their own accord (e.g., they may be heated). Or, thegeometry may be such that the clamps extend past the edges of thematerial to be embedded with wire, and so no cavities are required. Insome embodiments, multiple wires may be held by a single or multiplepairs of clamps, and embedded simultaneously (e.g., to differentdepths).

In some embodiments, the wire is not held by clamps at its two ends asshown, but may be held at other positions. For example, a long piece ofwire may be clamped at two locations near its center, and then thesegment approximately between the clamps embedded. Other segments of thewire can then be embedded at other angles (i.e., not collinear with thefirst embedded region), remain un-embedded to connect to other devicesor other wires, etc.

Since the wire is under tension, it must normally be straight betweenthe clamps; however, in some embodiments one or more structuresintermediate between the clamps (e.g., pins) may be provided so that thewire may follow a more complex path. In the case of straight wires, forexample, toolpaths can be automatically calculated that allow for therequired circuit or mechanical structure to be produced using straightsegments of wire, and cavities (if required) automatically generated toallow for clamps.

While the method of FIGS. 96(a), 96(b), 96(c), 96(d), 96(e), and 96(f)typically involves clamps that hold the wire, the methods of FIGS.70(a), 70(b), 70(c), 94, 95(a), and 95(b) may benefit from having oneend or segment of the wire anchored in the thermoplastic while embeddingmore of the wire. However, the end or segment, or a section nearby, mayneed to connect to another wire or element through a junction. In someembodiments, the end or segment may be anchored in dielectric material,but a cavity is provided adjacent to the end or segment that will laterbe filled with conductive material. In other embodiments, conductivematerial is provided before the wire is embedded, such that the wire endor segment can be anchored in the conductive material, as well as forman electrical junction.

Using embedding methods such as those shown in FIGS. 70(a), 70(b),70(c), 94, 95(a), 95(b), 96(a), 96(b), 96(c), 96(d), 96(e), and 96(f),the wire depth can be constant for a given wire (being in some casesembedded to a depth greater than the thickness of the last-fabricatedlayer), or may change along the length of the wire. In some embodiments,the wire may span multiple layers (e.g., within a dielectric,multi-layer object) and form a type of vertical interconnect, as shownin FIGS. 97(a) and 97(b). In FIGS. 97(a) and 97(b), the wire on layerN−3 remains in that layer, as does one wire on layer N−1. However, awire is depicted starting on layer N−1 and rising at an angle such thatit ends up entirely within layer N, bending to become parallel to it.Similarly, another wire is shown ascending at an angle from layer N−3(where is close to another wire) and terminating in layer N−1, where itsend is close to a wire already there. While smooth transitions fromlayer to layer are shown, in which the wire gradually changes depth,more abrupt transitions are also possible, as are curves in a verticalplane (wires may have a variety of shapes in the horizontal plane). Inboth figures, the fabricated object includes volumes penetrated by wiresin which there is no dielectric, but rather, a conductive material,allowing junctions to be formed. In FIG. 97(a), junctions are formedbetween wires using a conductive material (e.g., ECPC, conductive epoxy,solder, reflowed solder paste) that fills the volume, contacting thedielectric. In FIG. 97(b), junctions are formed by a conductive materialthat does not necessarily fill the volume, but which adheres to thewires and may be supported by them. In some embodiments, junctionsbetween wires (or between wires and other structures such as insertedcomponent pads and leads) may be formed by laser welding, ultrasonic orthermosonic wire bonding, conductive powder filling the volume, metalslike eutectic gallium-indium alloy which remain liquid at normaltemperatures, small “fuzz buttons”, wire mutual entanglement, wirewrapping (wrapping one wire around another), etc. For example, a cavitymay be formed within which are wires to be joined together. If thecavity is provided with a small aperture (e.g., on its top surface),then wire (e.g., of a smaller gauge than the wires being joined) can beinserted into the cavity so as to make contact, typically in multiplelocations, with the wires to be joined, forming a junction. Othermaterials, including conductive materials at least initially in liquidform, can also be introduced through such apertures to contact the wireswithin the cavities.

In some embodiments, wires can be embedded one above the other, eitheraligned or staggered, in an embedding operation that takes place betweenthe formation of two adjacent layers (if an AM process), rather thanembedding one wire in a particular X/Y location after each layer isformed. The lowest wire can be embedded first, followed by thenext-highest, etc., until all wires are embedded. Some wires may beembedded at a variable depth, as already described. Some embeddingdevices may provide for embedding multiple wires to multiple depths in asingle operation.

In general, wires embedded as described in FIGS. 70(a), 70(b), 70(c),94, 95(a), 95(b), 96(a), 96(b), 96(c), 96(d), 96(e), 96(f), 97(a), and97(b) can be of the same or mixed diameters, lengths, materials(including electrically non-conductive fibers such as optical or carbonfibers used for reinforcement or to make resistors), cross-sectionalshapes, etc. If wires are embedded close to the surface of the object,as shown in FIG. 94, where a simple cylinder may be used to press thewire into the surface, such that the cylinder cannot penetrate furtherinto the surface, in some embodiments, the wire may be capped by anadditional layer of dielectric material above it so that it is notexposed. In general, wires not completely surrounded by dielectric(e.g., embedded too deeply or not deeply enough, or laid along with theextrudate too close to the surface using methods such those shown inFIGS. 29(a), 29(b), 30(a), 30(b), and 30(c)) can be nonethelessinsulated as desired by making provision in the design and/or the“slicing” process that generates the layer cross sections for a cappinglayer above and/or below the wire.

Methods of embedding wire into already-deposited thermoplastic andmethods of simultaneously laying wire and depositing material such asthose shown in FIGS. 29(a), 29(b), 30(a), 30(b), and 30(c) may becombined in the production of a single fabricated object. For example,the latter method may be used to form a layer in which the wire isfairly deeply buried (e.g., at the bottom of the layer), and after thelayer is formed, the former method may be used to embed one or morewires above the previously-laid wire. The latter method in generalallows wire to be combined with non-thermoplastic materials (e.g.,thermosets), can be faster, since wire and dielectric are depositedsimultaneously, allows wire to help support poorly-supported structures,allows continuous structures like helical coils to be made, facilitatesor enables the formation of large regions of tightly-spaced wires, andenables embedding of especially delicate filaments (e.g., braided wireused in coaxial cable shielding, optical fibers). The former method ingeneral allows wires to be placed along paths that do not necessarilycoincide with the path of dielectric extrudates, and may facilitate useof wires that are taller than a single layer or wider than a singleextrudate. Nonetheless, the latter method also may be used to embed suchtaller or thicker wires, for example, by heating the wire and/or thesurrounding material using Joule/resistive heating, a localized hot airjet, laser, etc., such that as the wire is laid/co-deposited with thepolymer, it also can penetrate into material on the previous layerand/or to its side on the same layer.

In some situations, after either or both methods are used, the surfaceof the layer may be rougher and/or less planar then desired, or of theincorrect thickness, as a result of laying or embedding wire. Thereforein some embodiments the layer may be smoothed and/or planarized once thewire is in place, before continuing to build the subsequent layer (ifany) using a mechanism that softens and reflows the layer surface. Insome embodiments, the mechanism can be a heated roller which traversesthe layer surface or portion thereof. In other embodiments the mechanismcan be a heated plate which contacts the layer. With roller, plate, orother mechanism, the fabricated object may rise using the Z stage tocontact the mechanism, while the printhead is moved off to the side. Itmay be desirable to have the mechanism made from or coated with anon-stick material such as PTFE, and in some embodiments the mechanismmay comprise a thin sheet of material that is peeled off of the layerafter smoothing or planarizing.

In some embodiments, the pressure exerted on the object associated withembedding wires such as in FIGS. 70(a), 70(b), 70(c), 94, 95(a), 95(b),96(a), 96(b), 96(c), 96(d), 96(e), 96(f), 97(a), and 97(b), due to thewire entering the softened material, may distort or damage the objectand/or cause the wire to end up at the incorrect depth. An example of ageometry that may be difficult to embed with wire is a cantilever. Thisproblem may be mitigated in various embodiments through the use ofproper supports, through the use of a vacuum system that pulls thestructure to be embedded upwards during the embedding process, throughthe use of a temporary adhesive applied to the embedding device or anearby device, through the use of a magnet (if the material into whichthe wire is embedded, or nearby material, is magnetic), etc.

The methods depicted in FIGS. 70(a), 70(b), 70(c), 94, 95(a), 95(b),96(a), 96(b), 96(c), 96(d), 96(e), 96(f), 97(a), and 97(b) may in someembodiments be used in fabricating structures in which wire is embeddedafter a dielectric thermoplastic material is deposited, but not inregions that are intended to form junctions or cavities to receivecomponents. After embedding wire, junctions may be formed between wiresand between wire and other elements (such as pads on bare or packagedintegrated circuits) using deposited conductive material such as solder,solder paste, ECPC, or “fuzz buttons”, or by using bonding methods suchas laser welding, ultrasonic or thermosonic bonding, resistance welding(e.g., squeezing two wires together with electrode “tweezers”, such asthose made by Assembly Technologies International of Clawson, Mich.),resistance soldering, micro tungsten insert gas (TIG) welding (e.g.,using the PUK 5 welder of Lampert, Werneck, Germany), pulse arc welding(e.g., using the welders of Sunstone Engineering, Payson, Utah), etc.These methods may also be used in which the order of events is modified:for example, in which the conductive material is deposited after thedielectric material (or vice versa) and then the wire is embedded.

In some embodiments, a junction, or a portion of a junction, may befabricated by first fabricating a cavity in dielectric matrix material,through which at least one wire passes, with at some region of thewire(s) unencapsulated in matrix material (i.e., bare). The ECPC regionsshown in FIGS. 8(a) and 8(b) are examples of portions of a junction;such portions when adjacent are electrically shorted, forming ajunction. ECPC, solder, or other conductive material is then depositedinto the cavity, in some embodiment variations filling it at least inpart. In other embodiment variations the deposited conductive materialis deposited so as to contact the wire(s), but not necessarily (and insome embodiment variations, intentionally) not contacting the cavitywalls. ECPC, for example, may be deposited into the cavity by dispensingit from the nozzle of a filament extruder, a screw extruder (e.g., theextruder shown in FIGS. 145(a), 145(b), 145(c), and 145(d)), or a heatedtube equipped with a pressure source such as a piston. In someembodiments, the bottom surface of the nozzle is approximately even withthe top surface of the cavity, while in other embodiments, the bottomsurface is below the top surface, while in still other embodiments, thebottom surface is above the top surface. Having the bottom surface belowthe top surface of the cavity can help avoid ECPC (or other conductivematerial) from protruding above the top surface of the cavity. In someembodiments, the cavity, or a portion thereof (e.g., the upper surface)is rectangular (e.g., square) in plan view, while in other embodimentsit is shaped otherwise. For example, if the top surface of the cavityhas a reasonably accurate circular shape and/or is compliant, a conicalnozzle can fit into it and seal against the upper edge while injectingECPC, minimizing spreading beyond desired volume.

The nozzle can in some embodiment variations be oscillated (e.g.,vertically) to push/pack ECPC in a flowable state into the cavity,helping to increase contact between the wire(s) and ECPC, as well asconsolidating the ECPC to cause conductive particles to move closertogether and form better conductive percolation networks, therebyreducing ECPC resistivity. This can be particularly useful inhigher-aspect cavities (e.g., multi-layer cavities for inter-layerjunctions, in which ECPC is deposited only after the upper portion ofthe cavity is formed, rather than on all the layers of the cavity). Insome embodiments, a small protruding or extendible element such as acylinder or pin can be used to pack ECPC into the cavity and/or smoothits top surface (e.g., if heated). In some embodiments, junctions are“capped” by depositing at least one additional layer over the cavity toincrease the robustness of the junction and/or wire(s) being joined. Insome embodiments, the top layer of the cavity has an aperture smallerthan the layer beneath it, such that the ECPC cannot easily leave thecavity, if not sufficiently adherent to the cavity walls or wire(s), butthe junction is nonetheless exposed (e.g., to allow an electroniccomponent to be inserted, for example, in making an electronic package,as described below).

In some embodiments, rather than a small cavity which can be filled withECPC through a nozzle not moving in the X/Y (layer) plane, a largercavity (e.g., a trench) may be used, such that ECPC is deposited as anelongated extrudate within the cavity. The cavity may be wider at one orboth ends than the extrudate, to accommodate excess material that mightotherwise protrude above the top of the cavity.

FIGS. 98(a-c) depict in cross-sectional elevation view a junctionbetween wires in two adjacent layers (however, wires in the same layermay also be so joined) made within a cavity in the fabricated object,and used in some embodiments. As shown the junction is at the ends oftwo wires; however, it may be made along the length of one or both wiresin some cases. In FIG. 98(a), the wires are seen from the side, whileFIGS. 98(b) and 98(c) depict the junctions as seen in the direction ofthe arrow shown in FIG. 98(a). The conductive material forming thejunction may be deposited onto the wires after both wires are laid orembedded, by applying it to the wires and having it cling and bond tothem. For example, a drop of molten solder may be applied to the wires,such as using a nozzle dispenser, or a small amount of solder paste maybe applied and then reflowed (e.g., using a localized hot air streamdelivered by a unit such as the ZT-2-MIL Hot AirPencil made byZephyrtronics (Pomona, Calif.), or ECPC may be applied. In someembodiment variations, solder or solder paste can be applied to eachwire (each on a different layer) separately, and then, if the solder orpaste is in contact or near-contact, the two volumes of solder or pastecan be reflowed together to make a junction.

In some embodiments, the conductive material does not contact or atleast, not adhere to, the walls of the cavity as shown. Thus, thejunction is suspended by the compliant wires and largely isolated fromdeformations of the cavity wall which might otherwise strain it. Suchstrain may cause cracking, detachment of the material from the wires,de-percolation (in the case of ECPC), etc. While the wires may bealigned vertically as shown in FIG. 98(b), particularly in the case ofusing higher-viscosity conductive materials such as solder paste, it maybe advantageous in some embodiments for the wires to be staggered as inFIG. 98(c), such that the upper wire does not interfere with access ofthe material to the lower wire. In some embodiments, rather than beingsubstantially parallel as shown in FIGS. 98(a), 98(b), 98(c), 98(d),98(e), and 98(f), the wires may be at an angle (e.g., 45°, 90°, 180°(anti-parallel)) to one another. It should be noted that if a solderjoint (or an ECPC joint) such as those used in some embodiments of FIGS.98(a), 98(b), 98(c), 98(d), 98(e), and 98(f) were to become hot (due toincreases in the fabricated object's environment, Joule heating of thewire, etc.) and melt, the electrical functionality of the junction maybe preserved, especially in junctions in which care has been taken toisolate the joined wires from excessive strain, as described.

FIGS. 98(d), 98(e) and 98(f) depict junctions in cross-sectional planview. FIG. 98(d) depicts a junction used in some embodiments similar tothat of FIG. 98(a), but in which the wires enter the junction fromdifferent angles (e.g., at 90° apart as shown). In this arrangement,wires on the same layer can also be joined. Such an arrangement can behelpful in isolating the junction from stress and strain, and alsofacilitates (as with the arrangement of FIG. 98(c) the conductivematerial reaching the lower wire. FIG. 98(e) depicts a junction in whichthe wires leading to the junction undergo one or more bends en route tothe junction (in practice the bends may be more rounded than shown).This helps the wires be more solidly anchored within the surroundingdielectric, distributes any stress applied to the wires, and furtherisolates the junction from stress and strain. In FIG. 98(f), one or morewires entering the cavity are allowed to bend into a serpentine, spiral,or other pattern which adds length to at least one wire and providesmore compliance, further isolating the junction from stress and strain.The approaches of FIGS. 98(e) and 98(f) may of course be combined insome embodiments for a combined advantage.

FIG. 99 depicts a cross-sectional view of a stress and strain-isolatingjunction used in some embodiments. The figure can represent either anelevation view or a plan view. Wires enter a volume ofhigh-durometer/high-modulus of elasticity conductive material such as anECPC. This is surrounded by a medium-durometer/medium-modulus dielectricmaterial, and the latter is further surrounded by alow-durometer/low-modulus dielectric material (of which much of theobject may be composed). Due to the gradient in hardness/modulus, thestresses and strains of the junction are mitigated. In some embodimentvariations, the materials are mutually adherent, while in otherembodiment variation they are not. In some embodiment variations, moregradations in hardness/modulus may be used, and in some embodimentvariations, the gradient may be continuous, with material propertiesgradually varied in the vicinity of the junction. In some embodiments,the medium-durometer material shown in the figure may be eliminated,with the junction simply comprising a hard conductive materialencapsulating portions of at least two wires, the hard material embeddedwithin relatively soft material comprising the fabricated object.

FIG. 100 depicts a cross-sectional elevation view of several layers ofdielectric material with internal wires and with junctions betweencertain wires. In the current situation, it is desirable to connecttogether all the wires at their ends with a vertical “via” orequivalent. If a method (e.g., solder or solder paste) of forming thejunctions is used that can only span a limited number of wires (e.g.,two as shown) is used, then a satisfactory equivalent via may beachieved using a staggering approach. Such an approach may be requiredwhen there is a risk of reflowing a solder joint while attempting tocreate another one involving one of the same wires directly above it,for example. As shown in the figure, wires 1 and 2 can be connected atJunction A; wires 2 and 3 at Junction B, which is not aligned verticallywith junction 1; wires 3 and 4 at Junction C, which is not alignedvertically with Junction B but may be aligned as shown with Junction A;and wires 4 and 5 at Junction D, which is not aligned with Junction Cbut may be aligned with Junction B.

As shown in the cross-sectional elevation view of FIG. 101, in somecases, the junctions may be made using a conductive material (e.g., ahard ECPC) that is relatively high in modulus compared with thedielectric material, which may be a soft elastomer. Created a verticalvia of such material would potentially stiffen the fabricated object inundesirable ways. In lieu of a strictly vertical via, therefore, in someembodiments a staggered vertical via may be employed. In FIG. 101, itmay be observed that conductive material is used only in localizedregions that are discontinuous both along the layer stacking (i.e.,vertical) axis and along other axes, thus avoiding a stiffening effectwhile still allowing, all wires to be connected together as intended.

FIGS. 102(a), 102(b), 102(c), and 102(d) depict a wire cutting andfeeding apparatus used in some embodiments that is similar to that ofFIGS. 33(a), 33(b), 33(c), 33(d), and 33(e). In the current apparatus,however, as shown in the figures, the blade is not perpendicular to thewire axis, and moves along a path that is also not perpendicular to it,thus cutting the wire to create a beveled end. Moreover, the downstreamcapillary is enlarged in inside diameter. In FIG. 102(a), the wire isbeing fed normally by the rollers. In FIG. 102(b), the wire has stoppedbeing fed, and the blade has advanced to cut the wire against the anvil.In some embodiments, the wire can be cut by diamond blades, or byextremely sharp and thin steel blades such as the “Feather” blades madeby the Feather Safety Razor Co., Ltd. of Japan. It is highly desirableto not leave burrs on the wire that interfere with entering or passingthrough the capillary. To maintain blades in a sharpened state, bladescan be replaced as needed, and blades that have long cutting surfacessuch as Feather blades can be indexed parallel to the cutting edge sothat worn regions can be replaced with sharp ones. In FIG. 102(c), theblade has been withdrawn and in FIG. 102(d), the downstream segment ofwire has been retracted away from the blade (e.g., by advancing the wirefeeder/cutter and printhead without feeding more wire). The next timewire is fed, it will be able to enter the downstream capillary withoutdifficulty for several reasons: 1) the lower edge of the downstreamcapillary is lower than the anvil, such that the lower edge of the wirewill not catch on the edge; 2) the beveled surface of the wire tends topush the wire downwards and away from the upper edge of the downstreamcapillary as the wire advances, avoiding getting caught; and 3) the edgeof the retracted blade in some embodiments helps keep the wire down andaway from the upper edge. The downstream capillary, which in someembodiments is the last conduit for the wire on its way to the nozzle,may be provided with frictional means (not shown) such that wire insideof it cannot fall out of its own accord, but remains inside until pushedor pulled. Suitable frictional means include a spring such as a flexurecontacting the wire through a cutout in the capillary, an internalobstruction such as a crimped region, etc.

FIGS. 103(a), 103(b), 103(c), 103(d), 103(e), 103(f), 103(g), and 103(h)provide simplified schematic views of an apparatus such as that of FIGS.33(a), 33(b), 33(c), 33(d), and 33(e), or 102(a), 102(b), 102(c), and102(d), and a first method for feeding, cutting, and laying wire used insome embodiments to create an extrudate which contains wire in someregions and no wire in others. In FIG. 103(a), the printhead (includingthe extrusion nozzle and the wire feeder/cutter) is moving to the rightwhile the nozzle extrudes material (or equivalently, the object beingfabricated is moving to the left). In FIG. 103(b), as the printheadcontinues to move, the rollers advance the wire until it contacts themolten extrudate. In some embodiments wire is preferably not advanced tothis position until it is ready to be laid/encapsulated within theextrudate since the extrudate might (especially if cooling means areprovided) inadvertently capture it. This is especially true of shortpieces of wire which may be inside the downstream capillary and whichare too short to be reach the roller, which might otherwise retain them(though risking distortion or damage to the object). However, the wiremay be advanced to a position closer to the extrudate than that shown inthe figure.

In FIG. 103(c), as the printhead continues to move, the rollers continueto advance the wire into the extrudate until it is positivelycaptured/anchored. Then, as in FIG. 103(d), in some embodiments therollers disengage from the wire, separating as shown, or in otherembodiments simply stop being driven and become free to rotate withoutresistance. As the printhead continues to more to the right, the wireremains in place with respect to the fabricated object, entering theextrudate that is being deposited around it. While this occurs, wire isdispensed from a supply spool or similar as needed. In FIG. 103(e), theprinthead has in some embodiments stopped as shown (in other embodimentsif the cutting is rapid enough, or if stretching of the wire isdesirable before cutting, the printhead may continue to move, perhapsmore slowly) so as not to apply tension to the wire and risk pulling itout of the extrudate, damaging or distorting the part, etc. Also, theblade has moved into the wire (e.g., rapidly) to cut it. In FIG. 103(f),the blade has retracted, the rollers have re-engaged the wire (or nolonger rotate freely), and (in some situations, as shown) the printheadhas begun again to move and extrude, now that the wire is cut. In FIG.103(g), the printhead is moving to the write, forming extrudate withoutwire as shown. FIG. 103(h) is essentially equivalent to FIG. 103(a); theprinthead may continue to form pure extrudate, or as in FIG. 103(b),preparation for delivering wire may occur next.

FIGS. 104(a), 104(b), 104(c), 104(d), 104(e), 104(f), 104(g), and 104(h)provide simplified schematic views of an apparatus such as that of FIGS.33(a), 33(b), 33(c), 33(d), and 33(e), or 102(a), 102(b), 102(c), and102(d), and a second method for feeding, cutting, and laying wire usedin some embodiments which creates an extrudate which contains wire insome regions and no wire in others. FIGS. 104(a), 104(b), and 104(c) areidentical to FIGS. 103(a), 103(b), and 103(c), with the same eventsoccurring. However, this second method varies beginning with FIG.104(d), in that the rollers continue to feed wire. As the printheadcontinues to more to the right, the wire remains in place with respectto the fabricated object, entering the extrudate that is being depositedaround it. While this occurs, wire is dispensed as needed. In FIG.104(e), the printhead has in some embodiments stopped as in FIG. 103(e)and the blade has cut the wire. In FIG. 103(f), the blade has retractedand the printhead has (in some situations, as shown) begun again to moveand extrude. FIGS. 104(g) and 104(h) are identical to FIGS. 103(g) and103(h), with the same events occurring.

FIGS. 105(a), 105(b), 105(c), 105(d), 105(e), 105(f), 105(g), 105(h),105(e′), 105(f′), 105(g′), 105(h′), 105(i′), 105(e″), 105(f″), 105(g″),and 105(h″) depict simplified schematic views of an apparatus such asthat of FIGS. 33(a), 33(b), 33(c), 33(d), and 33(e), or 102(a), 102(b),102(c), and 102(d), and a method for feeding, cutting, and laying wireused in some embodiments in which extrudate having bare wire at each endmay be produced. In FIGS. 105(a), 105(b), 105(c), 105(d), 105(e),105(f), 105(g), and 105(h), bare wire of a medium length results at theright end of the extrudate, while in FIGS. 105(e′), 105(f′), 105(g′),105(h′), and 105(i′), which replace and supplement FIGS. 105(e-h), barewire of a long length results. In FIGS. 105(e″-h″), which replaces FIGS.105(e), 105(f), 105(g), 105(h), bare wire of a short length results.

In FIG. 105(a), the printhead (including wire feeder and wire) isadvancing to the right (or equivalently, the fabricated object moves tothe left). In FIG. 105(b), the rollers are activated, feeding wiretoward the nozzle as the nozzle continues to move to the right. In FIG.105(c), the nozzle continues to move and the wire continues to moverelative to the nozzle, until in FIG. 105(d), the wire has moved pastthe nozzle sufficiently to provide the desired length of bare wire atthe left end of the wire. At this point, extrusion begins as the nozzlecontinues to move to the right. In FIG. 105(e), the printhead hasstopped at a position which provides the desired medium length of barewire extending from the extruded material. Next, in FIG. 105(f), theblade cuts the wire (in some embodiments this may be done while theprinthead is moving, e.g., if moving slowly) and in FIG. 105(g), theblade retracts. The printhead then continues to move in FIG. 105(h),leaving behind the desired extrudate and wire composite.

In FIG. 105(e′) (replacing FIG. 105(e)), extrusion has been stoppedwhile the printhead continues to move to the right and wire is fed. InFIG. 105(f′), the nozzle has moved to a position suitable for cuttingthe wire so that a long length of wire will extend from the right end ofthe extrudate. In FIG. 105(g′), the wire is cut, during which timeprinthead motion relative the fabricated object may be paused, and inFIG. 105(h′) the blade is retracted. The printhead then continues tomove in FIG. 105(i′), leaving behind the desired extrudate and wirecomposite. In FIG. 105(e″) (replacing FIG. 105(e)), extrusion is stoppedand printhead motion is stopped (in some embodiments the printhead maycontinue to move, e.g., slowly). In FIG. 105(f″) the wire is cut and inFIG. 105(g″) the blade is retracted. In FIG. 105(h″), the printheadcontinues to move forward while extruding, leaving behind only a shortlength of bare wire extending from the right end of the extrudate.

Feeding and cutting methods similar to that in FIGS. 103(a), 103(b),103(c), 103(d), 103(e), 103(f), 103(g), 103(h), 104(a), 104(b), 104(c),104(d), 104(e), 104(f), 104(g), 104(h), 105(a), 105(b), 105(c), 105(d),105(e), 105(f), 105(g), 105(h), 105(e′), 105(f′), 105(g′), 105(h′),105(i′), 105(e″), 105(f″), 105(g″), and 105(h″) can be used in someembodiments in embedding approaches such as those of FIGS. 70(a), 70(b),70(c), 94, 96(a), 96(b), 96(c), 96(d), 96(e), 96(f), 97(a), and 97(b) aswell as in simultaneous extruding and wire laying approaches such asthose shown in FIGS. 29(a), 29(b), 30(a), 30(b), and 30(c).

In some embodiments, it is desirable to introduce multiple wires into asingle extrudate at a time. For example, the current-carrying capabilityof a coil may be increased by using thicker wire, but such wire may bedifficult to incorporate due to its stiffness, or in the case of acompliant structure, the stiffness may be undesirable. Thus, layingmultiple strands of thinner wire through a single or multiplecapillaries is a desirable alternative. Since it is common for anextrudate to be wider than it is tall, these multiple strands in someembodiments can be positioned side to side, and can of course be inelectrical contact with one another. Multiple wires may also allow formore redundant contacts with ECPC, allowing alternative percolatingpathways to be used; this can be particularly useful if there is a riskthat some pathways are disrupted, e.g., by overly stressing andstraining the ECPC. Moreover, multiple wires are likely to be radiallymore distributed through an ECPC junction than a single solid wire, thusreducing the average distance of wire in one junction to that of wire inan adjacent junction.

In some embodiments, multiple wires may be embedded in a singleextrudate for the purpose of increasing circuit density, e.g., to matchthe density of pads on an integrated circuit (bare die or packaged), toincrease current-carrying capacity (e.g., filling more of the volume ofthe extrudate, especially laterally, with metal, without using a stiffwire or one which is difficult to deform laterally along a curvedtoolpath), mechanical strength or stiffness, etc. The wires may differin size, shape, composition, etc. The relative location of the wires inthe extrudate may vary (e.g., side-to-side, one above the other, etc.).In cases which require the wires to be electrically isolated, this canbe achieved by using insulated wires (e.g., lacquer insulation as withmagnet wire) or by incorporating dielectric fibers between the metalwires as spacers, or by passing currents through the wires as they aredeposited so as to cause them to repel so that the dielectric polymercan separate them, etc. In some embodiments a “rake” may be provided onor near the nozzle which has tines which keep multiple wires apart untilthey are embedded in solidified matrix material. In some embodiments,multiple wires may be used to create more complex wire cross-sectionalshapes, such as shields which surround a central conductor to form acoaxial cable. When more than a single wire is incorporated into asingle extrudate, each wire can be fed passively or actively (e.g.,using a feeder/cutter such as that in FIGS. 139(a), 139(b), 139(c),139(d), 139(e), 139(f), 139(g), and 139(h)). If fed actively, wires insome embodiments may be fed at different speeds. For example, inproducing a coil in which two wires are located side-by-side in the sameextrudate so as to increase current-carrying capacity of the winding,the wire on the outside of the turn needs to be somewhat longer, andthus, should be fed at a faster rate. In the case of multiple wires in asingle extrudate which should not touch (e.g., for a batteryapplication), by feeding the wire on the outside of a turn significantlyfaster than the wire on the inside, separation between the wires can bemaintained with little if any need for a spacer.

In some embodiments, by adjusting the relative feed rates of two or morefibers encapsulated within the same extrudate, the matrix material, byclinging to the fibers, can be “steered” to follow a particular path bythe relative feed rates of the wires (i.e., straight if the rates arethe same, curved if they are different).

In some embodiments stranded wire may be used in lieu of solid wire.Stranded wire is typically more flexible, and can have more surfacearea, thus providing less contact resistance with ECPC. Stranded wireprovides redundancy, in that the breakage of a single strand does notinterrupt the circuit.

FIGS. 106(a) and 106(b) depict in plan views a structure having somesimilarities to the structure of FIGS. 59(a), 59(b), and 59(c) forintegrating a device such as an integrated circuit (e.g., a bare die,surface mount package, or through-hole package) or other electronic orelectrical device with a fabricated object. In one application, thestructure may take the form of a 3-D printed circuit board (PCB), and inother applications, it may be a part of a larger system. Indeed, as anaside, FEAM may be used to construct PCBs, whether conventionally planaror 3-D, using for example copper wire as the interconnect, a(preferably) high temperature thermoplastic (e.g., nylon or PEEK, thelatter available in filament form from INDMATEC GmbH (Karlsruhe,Germany)) or thermoset material such as polyimide or epoxy, or (for aflexible circuit) silicone elastomer as the dielectric. Solder jointsmay be made between inserted or surfaced mount components and wires,e.g., with low-temperature solders.

In FIG. 106(a), wires are shown buried within dielectric, with cavitiesthrough which the wire passes (in some embodiments the wires mayterminate inside the cavities, while in other embodiments the wiresextend past the cavities so they can be better anchored in thedielectric). The cavities are laid out to match pads, pins, or otherterminals on the device. In FIG. 106(b), the cavities are filled (e.g.,using a nozzle or pneumatic dispensing system) with a material suitablefor making electrical contact to the device. In some embodiments, thematerial may protrude beyond the dielectric surface, and in someembodiments, the material may be elastomeric. For example, the materialmay be ECPC, solder paste, conductive epoxy (e.g., E3082 from EpoxyTechnology, Inc. of Billerica, Mass.), or other materials. In the caseof ECPC, the ECPC may be pre-heated (e.g., by localized hot air flow) tosoften the TPE and make it tacky, and the device picked up andpositioned (e.g., by a vertically-translating vacuum pickup mounted tothe stage holding the printhead) and pressed onto the ECPC pads so thatits terminals make contact. In some embodiments structures which allowself-assembly (e.g., fluidic self-assembly or vibrational self-assembly)may be fabricated, such as specially-shaped cavities and rampedstructures, allowing devices to be positioned more efficiently,especially large numbers of devices. In the case of solder paste, thedevice may be similarly placed on the paste regions, and a localizedheating system such as the ZT-2-MIL used to reflow the solder,preferably after pre-heating the paste to activate the flux. In someembodiments, the paste may be pre-heated as it is dispensed (e.g., usingan inline heater); in some embodiments the object may be built inside achamber at a temperature that activates the flux, and in someembodiments the layer or portions therefore may be exposed to a heatsource such as an infrared light. In the case of conductive epoxy, thedevice may be similarly placed on the regions of epoxy, and a similarlocalized heating system used to rapidly cure the epoxy (unless aUV-curable epoxy is used, in which case a UV LED or other source can beused).

After the device is attached to the conductive material, the device maybe father secured by dispensing an underfill known to the art in theelectronics industry, by dispensing dielectric polymer (thermoplastic orthermoset, including UV-curable) onto at least part of it, etc. In thecase of a through-hole package, the pins of the device may be insertedinto a soft conductive material such as partially melted hard ECPC orunmelted soft ECPC. With elastomeric ECPC, the device may simply bepressed so that its terminals contact the ECPC, and kept compressed bysuitable underfill or capping material (including additional depositedlayers), etc. Structures similar to that of FIGS. 106(a) and 106(b) maybe created on other planes (e.g., vertical, parallel to the Z axis) of afabricated object, or on curved surfaces to integrate ICs and otherdevices at other angles.

Formation of metal volumes that are much larger than individual wires(continuous sheets, or nearly-continuous regions such as sheetsseparated by thin dielectric volumes that serve the purpose oflaminations to reduce eddy currents) is an important capability. Such acapability allows for 3-D printing objects comprising soft magneticarmatures and cores needed for solenoids and for magnetic circuits ingeneral, capacitor plates, ground planes that are mostly continuous (vs.made from closely-spaced wire, another option), patch antennas, thermalmanagement structures (which can also be made from wire, ECPC, etc.), RFshields, mechanical structures including reinforcing elements, etc.Several approaches to this may be used, in various embodiments.

One approach is the layer-by-layer spiral winding approach shown in FIG.12. A second approach is to deposit a metal powder either by itself oras a composite material. ECPC is one such composite, intended forelectrical conductivity, and an analogous composite that providesmagnetic permeability comparable to solid ferromagnetic material such asiron can also be produced and deposited. SMPC's (“soft magnetic polymercomposites”, a.k.a. “soft magnetic composites”, or SMC's) may consist ofsmall particles of a magnetically soft metal such as iron (e.g. Atomet1001HP from Rio Tinto Metal Powders, Sorel-Tracy, Quebec, Canada) mixedwith a suitable binder (which might not always be a polymer). In someembodiments the powder may be coated with a binder (e.g., athermoplastic) such that, once formed into the desired shape (e.g., bybeing delivered into a cavity), the binder can holder the particlestogether (e.g., by heating the powder and allowing it to cool). Acommercially available SMPC with a relatively low concentration offerromagnetic material is the magnetic iron filament (iron particlesmixed with PLA) made by ProtoPlant (Vancouver, Wash. Otherfinely-divided metals may be used, such as nickel, steel, and cobalt.One example is silver-coated nickel particles such as Potters SN08P40,which can also serve as ECPC. The binder may be in some embodiments athermoplastic polymer such as Nylon-6, Nylon-12, ABS, polylactic acid,or a thermoplastic elastomer; a soft wax such as paraffin or a hard waxsuch as Crystalbond (Aremco Products Inc., Valley Cottage, N.Y.), athermosetting or UV-curable adhesive such as epoxy, a non-thermosettingadhesive such as cyanoacrylate, a non-hardening material such as grease,a liquid such as oil, water, or alcohol, or other material. ECPCs andSMPCs may be extruded from a nozzle on a layer-by-layer basis to formthe shape desired. Alternatively, they may be extruded or otherwisedeposited into cavities formed in another material such as the primarystructural material used to build the object; such cavities may bemultiple layers in depth.

With regard to SMPCs, it is important that the volume fraction of softferromagnetic material be high in order to obtain the best properties,and suitable mixing approaches can be used to achieve this. In someembodiments, a magnetic field can be applied to compact (and align) thepowder particles within the binder, improving final properties. In someembodiments, however, it is desirable to eliminate the binder entirely.For example, a cavity may be filled with pure iron powder which ispreferably compacted by pressure (not to exceed that tolerated by theobject) and/or vibration. In some embodiments, powder can be mixed witha vehicle such as a solvent or water whose surface tension pulls theparticles together into a compact mass and evaporates.

A third approach to creating dense soft magnetic elements, which iscompatible with low-temperature materials, is cold spray or relatedtechnologies such as capillary cold spray and plasma spray. With suchmethods, iron or other suitable materials can be deposited to formstructures with low porosity, such as filling a cavity with a capillarycold spray system that directs material into the cavity.

A fourth approach is the laying or embedding of wires side-by-side withlittle or no gap between them. In some embodiment variations, theside-by-side wires are straight and the desired shape is approximated bycut wires forming a typical “rasterized” representation of the shape. Inother embodiment variations, the side-by-side wires are curved in auseful direction but the ensemble of wires nonetheless forms the desiredshape. Wires may lie parallel to the layer plane or at angles to theplane, such as in FIGS. 97(a) and 97(b). In some embodiments, coilsproduced adjacent to rasterized patterns of magnetic wire (e.g., forminga solenoid coil) are preferably made square or rectangular vs. circular,so they can be located more closely to the magnetic wire, for maximumefficiency.

FIGS. 107(a), 107(b), 107(c), 107(d), and 107(e) are cross-sectionalelevation views of an asymmetric printhead nozzle designed to lay wire(in this case, square or rectangular wire) side-by-side, whetherstraight or curved (straight will be assumed in the followingdescription), retained by the material extruded from the nozzle, whichin general should be flowable and adhere to the wire and itself, andwhich may be dielectric, conductive, and/or magnetically permeable. Insome embodiments, the material is solidifiable, obtaining its maximumadhesion strength once fully solidified. In FIG. 107(a), the nozzle isshown positioned above a build substrate/platform (or the previous layerof the fabricated device). The gap between the flat surface near thebottom of the nozzle may be set to be approximately equal to the heightof the wire to be laid (however, if wire that is not square orrectangular wire is used, the surface may be shaped to match the wire).Thus in some embodiments the wire height and the layer thickness areequal. In some embodiments, the bottom of the nozzle serves as a doctorblade to ensure that little if any material (especially if dielectric)remains on top of the wire (in some embodiment variations aspring-loaded blade may be used to help keep the top of the wirerelatively free of material), while in other embodiments a larger gapmay be used, for example, to allow material to flow underneath the wireto anchor it and/or isolate it from wire or other structures underneath.The nozzle comprises a guide which in some embodiments is not centeredon the nozzle orifice and which in some embodiments extends below theflat surface; the guide may have a height such that it does not touchthe substrate. The guide serves to precisely position the wire in thelayer (X/Y) plane so that it conforms to the toolpath followed by theguide (in some embodiments this is useful even when laying wires morewidely separated), to precisely control the gap between adjacent wiresand prevent this from increasing due to fluid between adjacent wires,and as a stop to prevent material from coating the left side of thewire. In some embodiments, the guide is not an integral part of thenozzle but is a separate piece, and in some embodiment variations, theguide may be moved separately from the nozzle according to a distincttoolpath/trajectory. In some embodiments, more than one guide may beprovided, or a guide with multiple guiding features may be used. In someembodiments, the guide has the form of a groove or female featureinstead of a projection or male feature. In FIG. 107(b), wire has beenplaced below the nozzle (e.g., extended from a suitable capillary, suchas a square capillary that prevents wire rotation) such that the wire isheld downwards against the substrate by the flat surface on the bottom,or by the flow of material (e.g., thermoplastic, though other materialsmay be used) issuing from the nozzle. Meanwhile, since the wire isoffset from the axis of the nozzle orifice, the flow tends to push thewire up against the inner wall of the guide, which serves to stop andaccurately position the wire along the X axis. In some embodiments, thewire, if ferromagnetic (e.g., nickel) may also be attracted to the guideif the latter is ferromagnetic and connected to a permanent magnet orelectromagnet, or if a magnet such as a permanent magnet (preferablythermally isolated from the nozzle) is located to the left of the guide(not shown). In this configuration, the printhead then moves out of theplane of the drawing, extruding material at a suitable flow rate tosecure the wire in place by anchoring it to the substrate.

In FIG. 107(c), the printhead has moved to the left in some embodimentsby a distance in excess of the wire width plus any desired gap betweenwires (this is non-zero if the goal is to produce a laminated structurein which adjacent wires are separated in the X/Y plane by a thin film ofdielectric, for example), while in other embodiments it moves only by adistance equal to the wire width plus any desired gap between wires. Inthe former case, the additional space between the guide and wire canfacilitate entry of the dielectric material into the gap between thewires, which might otherwise be high aspect-ratio. In this case, thenozzle moves to the right before or during the wire laying process asshown in FIG. 107(d). Also in FIG. 107(c), another wire is introducedbeneath the nozzle between the already-laid wire and the guide. In FIG.107(d), the printhead has moved again out of the plane of the drawing,laying the second wire and also depositing material between the twowires that separates them and anchors the second wire (the wire can alsobe anchored by some material flowing underneath, and by material at itstwo ends), as may be seen better in FIG. 107(e). Since the moltenmaterial is in contact with both wires simultaneously, they are bondedtogether properly. The material, delivered at an appropriate flow rate,may not completely fill the gap between the two wires, depending on thegap aspect ratio and operating conditions, and in some embodiments thisis acceptable if not desirable. In some embodiments, the guide may beangled or curved in a plane parallel to the substrate so that theseparation between the wire being laid and the previously-laid wire isinitially greater, allowing material to flow more easily into the gapbetween them. In FIG. 107(e), the printhead has moved to a position atwhich it can accommodate a third wire and the gap between it and thesecond wire. The process continues until all wires are laid. In someembodiments, wires are laid bidirectionally, with a new wire added eachtime the nozzle moves either into or out of the plane of the drawing.The process can continue on another layer, laying wires on top of wires.When the goal is to produce a laminated structure similar to that foundin conventionally-fabricated electromagnetic devices, the wires onsuccessive layers may be aligned along the X axis, such that dielectricmaterial-filled gaps also align, and form isolating, vertical planes.Otherwise, the wires may be staggered (e.g., like bricks) on successivelayers, shorting the wires together. The nozzle of FIGS. 107(a), 107(b),107(c), 107(d), and 107(e) allows wires to be laid from right to left;if another direction of laying wire is required, the nozzle can berotated about the orifice axis, or another version (e.g., a mirrorimage) can be used.

In some embodiments wires are laid with a larger gap, and the printheadreturns to push the wire to the final, desired gap using the guide,while the material is still able to flow. In some embodiments, thematerial is dielectric (e.g., to form laminations to minimize eddycurrents), while in other embodiments it is conductive (e.g., ECPC) toelectrically bridge the gap between the wires. The material may also bemagnetic (e.g., SMPC) to magnetically bridge the gap. In someembodiments, a different style of nozzle than that shown in FIGS.107(a), 107(b), 107(c), 107(d), and 107(e) is used. In such embodiments,the orifice is offset to the left relative to the wire, instead of tothe right as in FIG. 107(b), and material is deposited between the wireand the guide, which now has the function of a trowel or similar formerof soft material. The guide can be shaped (as seen from above,perpendicular to the layer plane) to incorporate a relief area thatallows extruded material to enter the space between the guide and thewire in the direction of the travel; the portion of the guide in directcontact with the wire still serves as a doctor blade to remove excessmaterial from the side of the wire if desired. Since material may remainon the left side of the wire after the wire is placed, the position ofthe nozzle along the X axis should be carefully set so that thethickness of this material is accommodated.

In some embodiments, the wire is heated to facilitate penetration of theextruded material, e.g., into a high aspect ratio gap such as that shownbetween the two wires in FIG. 107(d), minimizing freezing of thematerial entering the gap. In some embodiments, in which the gap isparticularly small or intended to be non-existent, the left and/or rightsides of the wire may be textured, scalloped, or otherwise shaped to benon-planar (e.g., by running the wire through an embossing roller, andpossibly two additional flattening rollers on the top and bottom toflatten out any burrs caused by embossing). As a result of the non-flatsides, material can still be injected between the wires to help bondthem together and bond them to the substrate or previous layer. A fourthapproach to forming large metal areas and volumes in a manner compatiblewith additive manufacturing is the use of cold spray and/or plasma spraytechniques known to the art (e.g., for coatings). These methods may beused to deposit magnetically-soft materials as well aselectrically-conductive materials, achieving high volume fraction ofmetal/low porosity.

A fifth approach to forming large metal areas and volumes isco-depositing foils with extruded material, in lieu of wire, orembedding foils into previously-deposited material. In such an approach,the foil may be continuous or may be perforated to allow material suchas molten polymer to penetrate it and encapsulate it. In the extreme,the foil may be in the form of a mesh.

The printhead in FIGS. 78(a) and 78(b) may be used to deposit dielectricpolymer and ECPC, for example, switching ‘on the fly’ between these twomaterials. Thus a junction such as those shown in FIGS. 8(a) and 8(b)can be generated, by transitioning from one material to another whilelaying wire. In some embodiments, however, it is desirable to depositeach material from its own nozzle, for example, switching between thetwo nozzles using a slide or turret. Moreover, in some embodiments it isdesirable to deposit ECPC in another direction than parallel to thewires. For example, ECPC may be anisotropic in its conductivity (e.g.,more conductive parallel to the long axis of the extrudate than acrossit/radially). Such an ECPC may preferentially be deposited in a cavityor trench formed in the dielectric material, such that the cavityincludes two or more wires on the same layer as in FIG. 8(a), with thenozzle moving perpendicular to the wires as the ECPC is extruded intothe cavity. Similarly, wires on separate layers such as in FIG. 8(b)would preferably be joined by ECPC that is extruded vertically to fill acavity common to the wires.

In some embodiments, regions of a layer that would normally be poorlyadhered or fused to material underlying or adjacent on the same layermay be subjected to localized heating to “tack weld” them. An example ofthe use of such an approach is an extrudate or group of extrudates thatoverlap extrudates on the layer below very little (e.g., the extrudatesare right angles to one another). Localized heating may be performedusing a system such as the ZT-2-MIL, an infrared laser, a spot infraredsource, etc.

Some materials, both pure and composite (e.g., ECPCs, PMPCs, and SMPCs)may degrade if they remain heated in a printhead for an extended period,with altered properties or extrusion performance being the result. Insome embodiments filaments of such materials may be extracted from theprinthead (e.g., by reversing the rollers or blades) when the controlsystem determines they will not be used for some time, during which timethey are likely to degrade. Or, if delivered by a separate nozzle andextruder, the temperature of the nozzle and extruder can simply bereduced temporarily, and increased again before the material needs to bedispensed, again by “looking ahead” in the data controlling thefabrication process to determine when the material will be needed.

Laying encapsulated wire with very small radii using approaches such asthat of FIGS. 5(a), 5(b), 5(c), 5(d), 29(a), 29(b), 30(a), 30(b), and30(c) can be facilitated in some embodiments using the “stapling”approach of FIG. 52, or by bending the wire around a form such as smalldiameter pin. For example, such a pin may be attached to the nozzle andmay be retractable, or may remain extended, dragging through moltenmaterial with little resistance, and if small enough in diameter,leaving the polymer minimally disturbed.

As already described, toolpaths may in some embodiments be calculatedand then implemented to generate extrudates with encapsulated wire asthe highest priority, and extrudates without wire as a lower priority.FIGS. 108 (a), 108(b), 108(c), and 108(d) depict an approach to this inwhich wire and polymer are deposited, followed by pure dielectricpolymer, followed by ECPC or other conductive material. In FIG. 108(a),the wire paths and cavities for the ECPC are calculated first, and willbe implemented as shown in FIG. 108(b). Then, in FIG. 108(c), toolpathsfor depositing extrudates encompassing the remaining dielectric polymerneeded on the layer are determined. Finally, toolpaths to deposit theECPC are determined.

Materials

In addition to SMPCs, it can be advantageous to incorporate permanentmagnetic materials into a fabricated object, allowing such devices asvoice coil actuators, permanent magnet motors, and many others to befabricated. While it is certainly possible to pause the fabricationprocess as is known in the art, and then insert magnets (not to mentionother items such as bearings, balls, semiconductor devices, etc.), itmay be preferable to fabricate magnets in-situ as part of an automatedprocess. PMPCs (“permanent magnet polymer composites”) may be formulatedfrom magnetic powders such as strontium ferrite, samarium-cobalt, andneodymium-iron-boron, mixed with a suitable binder such as the bindersdescribed above in the context of SMPCs. As with SMPCs, it is importantthat the volume fraction of ferromagnetic material be high in order toobtain the best properties, and suitable mixing approaches can be usedto achieve this. Or, pure permanent magnetic powders can be formed intocompact masses using techniques described above for soft magneticmaterials. In some embodiments, a magnetic field can be applied tocompact (and align) the powder particles within the binder, improvingfinal properties, as is sometimes done with in the mold when makinginjection molded magnets.

3-D printed permanent magnets need to be magnetized. This can be done byplacing the object containing the magnet(s) in a magnetic field afterfabrication. It can also be done in some embodiments by magnetizing themagnets before the object is completely fabricated, i.e., during orafter the permanent magnet material is deposited. In some embodiments,the deposited magnetic material may be placed in contact with or near apermanent magnet or electromagnet, and in some embodiments themagnetization is performed gradually and repeatedly, as more and morelayers are added to the fabricated magnet. In the case of a fabricatedmagnet which needs to be magnetized in an orientation which is noteasily accessible to a magnet used to magnetize it, or which is too deepinside the structure to be reached with that magnet, soft magneticstructures built into the object can be used to deliver the magnetizingflux to the magnet. These structures may be permanent in someembodiments, forming part of the magnetic circuit of a functionalmagnetic device. In other embodiments, the structures may be temporary,and be removed after the object is fabricated. For example, an SMPCcomprising a low melting temperature (e.g., a wax) binder, or a solublebinder (e.g., polyvinyl alcohol or PVA) may be removed easily: one thebinder is melted or dissolved, the particles simply fall away.

In some embodiments, custom-sized and shaped magnets may be fabricatedwithin a machine in a separate operation, such that they can beoptimally magnetized, then simply inserted into the build.

An example of a thermoplastic polymer that may be used with FEAM isKraton G1643M, a low-durometer (52 Shore A) elastomer. Such a polymermay also be mixed with conductive particles to form a compatible ECPC.For example, silver-coated hollow glass microspheres such as PottersSH400S20 (13 μm average diameter) may be mixed with D1161; the lowdensity of the hollow microspheres facilitates mixing by reducingsedimentation, and is cost-effective on a volumetric basis. Polymer orceramic particles coated with conductive material such as silver arealso suitable, as are solid metal particles (e.g., silver, nickel,copper), carbon particles, and nano-particles (e.g., carbon nanotubes).Smaller particles (e.g., 10-50 μm) are preferred, in part for theirlower likelihood to bridge and clog the printhead nozzle. Silver-coatednickel particles such as Potters SN08P40 and SH400S20, or silver-coatediron particles such as Potters SI03P40 are useful not only for theirelectrical properties, but for incorporating ferromagnetic elements suchas solenoid cores, plungers, and armatures with good properties; suchmaterials can be deposited into appropriately-shaped cavities/trenchesformed within the fabricated object. In some embodiments, adhesionpromoters may be mixed into the polymer to promote adhesion to theparticulate material, which can make the ECPC more robust against damagedue to large strains.

An example of a procedure using simple equipment that may be used toproduce ECPC filament with 35% by volume of powder uses about 12 gramsof G1643Mpellets, as follows:

Vacuum dry G1643M pellets for about 10 hours.

Measure out 11.6 grams of G1643M TPE and 66.0 grams of SN08P40conductive filler into separate containers.

Heat the G1643M pellets in a melting pot to ˜200° C.

Add SN08P40 carefully to the melting pot, minimizing powder clinging tosides of the pot.

Gently stir and press the powder into the TPE, so that the powdercontacts the softening TPE.

Cover the pot and heat to approximately 200-220° C.

Continue to mix the powder in by hand until a uniform color darker isreached.

As the powder becomes more absorbed into the TPE, stir more vigorously.

Mix using an electric mixer on a low speed setting for at least 60seconds. If temperature of the mixture has dropped, cover and reheat to200-220° C.

Repeat the above process 2-4 times until the contents of the pot startsto appear slightly wet and possibly beginning to clump, as opposed toappearing dusty.

Reheat again at 220-230° C.

By hand, stir the mixture in a large circular motion. The contents ofthe pot should suddenly clump together quite easily and form a single,large “dough-ball”.

Immediately transfer the dough-ball to an injection molder which shouldalready be pre-heated to ˜146° C.

Use the injection molder to extrude the material through a die (e.g.,1.75 mm diameter) at a constant speed.

In addition to blending powder with polymer in liquid form, ECPC can bemade by dry-blending polymer (e.g., powdered (perhaps cryogenicallyground)) and powder, by coating polymer with powder using a ball orvibratory mill, etc.

Particulates which may, in some embodiments, be used to advantage inFEAM include:

Ceramic powder or other additives that alter dielectric constant (e.g.,lowering it for high frequency applications using hollow microspheres),thermal conductivity, coefficient of thermal expansion, and otherparameters. For example, incorporation of ceramics such as boronnitride, aluminum nitride, beryllium oxide, and silicon carbide canincrease thermal conductivity without rendering the polymer matrixelectrically conductive. This can enable better heat dissipation fromwires, allowing higher currents to be used (e.g., for higher-forceactuators).

Conductive particles such as nickel and iron can be incorporated atconcentrations below the percolation threshold to nonetheless improvemagnetic properties of the resulting composite due to their highpermeability, improving the performance of electromagnetic devices(e.g., the actuators of FIGS. 26(a) and 26(b)). Coated (e.g., heavilyoxidized or encapsulated) conductive particles can also be used, as canferrites, which be used in FEAM-fabricated transformers, coils, and thelike.

Pigments may be added to polymers and other materials to color them, andsmall particles, whether pigmented or not, may be added to makeotherwise-transparent materials translucent or opaque by means ofscattering. For example, a region of a fabricated object able to diffuselight from an embedded LED or optical fiber might be produced using suchparticles.

Electroactive polymers such as those made by Novasentis (Burlingame,Calif.) may be incorporated into objects fabricated using FEAM. Powderedlead zirconate titanate (PZT) may be added to polymers used in FEAM tocreate piezoelectric actuators and sensors, as in PiezoPaint™ (MeggittSensing Systems, Dorset, U.K.), and wire and ribbons of piezoelectricmaterial may also be used. In some embodiments, piezoelectric elementsmay be fabricating from materials such as polyvinylidene fluoride orpolyvinylidene difluoride (PVDF) which are poled during the fabricationprocess and which use encapsulated wires as electrodes. Piezoelectricdevices may be used as actuators or as generators of electricity,depending on the application.

The incorporation of iron or other materials in finely-divided form intoan elastomer matrix gives rise to a magnetorheological elastomer, whichcan be based on thermoplastic elastomers [Bose and Roder, 2009]. Uses ofsuch materials in FEAM include stiffness modulation and haptic feedbackdevices, including those in which the magnetic field is generated bycurrent flowing in conductors embedded within the structure.Electrorheological elastomers are also possible.

Mechanical properties may be changed dynamically on a local basis byincorporating materials which undergo a phase change (e.g., wax) whenheated or cooled, and heating or cooling elements may be incorporatedinto a FEAM structure (e.g., resistive wires).

Bioresorbable polymers such as polylactic acid,polylactide-co-glycolide, or combinations thereof, can be used in FEAMto make structures and scaffolds incorporating filaments such as wiresas well as other components (e.g., integrated circuits) in specificgeometric, mechanical, optical, and/or electrical configurations. Whenthe polymer is resorbed, the configurations remain in place, and maybecome integrated into and/or infiltrated with living tissue to serve,for example, as active implants or bionic devices.

Electroluminescent materials may be incorporated into FEAM-producedstructures to provide light, for example, creating glowing elastomericstructures similar to those produced with Elastolite (OryonTechnologies, Addison, Tex.), but with more complex and 3-D shapes. Forexample, phosphors are available in small (e.g., 5 μm) particle sizesfrom companies such as PhosphorTech (Kennesaw, Ga.); these can beincorporated into polymer and if stimulated using appropriate electrodes(e.g., suitably-shaped wire) at suitable frequency, emit light. Polymerlight-emitting electrochemical cells [Lian and Pei, 2014] can beproduced with FEAM. Using electroluminescent materials, organic lightemitting diodes, etc., and materials which can change their opacity suchas liquid crystals, then displays can be produced with additivemanufacturing, including volumetric 3-D displays in which the 3-Dinterconnects to pixels, groups of pixels, or driver and multiplexingICs are built-in.

Haptic and certain kinds of 3-D displays may be produced with FEAM, forexample, a surface with an array of electromagnetic actuators thatdeforms itself dynamically to form a moving, bas-relief 3-D human facefor more realistic teleconferencing, a configurable, dynamictopographical map, a braille display, etc. In some embodiments, touchsensors may be embedded within the display surface so that it canrespond (e.g. by changing its shape) to touch and manipulation. A devicecan be created comprising a “blob” made from an elastomeric orplastically-deformable material, laden with sensors that can measurelocal deformation. Manipulating and deforming this “electronic clay”would be useful as a 3-D input device for creating or modifying CADmodels, for measuring strength and range of motion forrehabilitation/physical therapy, etc.

Heating elements and devices incorporating buried, integrated heatersmade from resistive wire may be made with FEAM. The generated heat canbe used to modify liquid surface tension to move/deform liquids (e.g.,for lab-on-a-chip devices and variable-focus lenses); process materials(e.g., perform the polymerase chain reaction); serve as electronsources; modify mechanical or other physical properties such asstiffness, such as in a structure containing a shape memory alloy, ashape memory polymer, a meltable metal or polymer such as wax, etc.;melt solder, etc. to make electrical connections (such localized meltingis especially useful if one can't heat the entire device); enhanceinterlayer and/or inter-extrudate adhesion; smooth surfaces offabricated objects using surface tension (e.g., for optical elements,and transparent regions of parts); de-icing (e.g., of UAV wings) anddefogging (e.g., of optical surfaces); sensors (e.g., for gas, or hotwire anemometers); and to enable displays such as those incorporatingthermochromic materials.

Touch-sensitive surfaces (e.g., for displays) comprising (e.g.,) crossedsets of small-diameter wires may be made using FEAM. One example isprojected capacitance touchscreens and sensors. If the surface must betransparent, the polymer can be reflowed in some embodiments by heatingit after extrudates are deposited such that surface tension smoothes thesurfaces; alternatively, the surface may be placed in contact with asmooth, heated non-stick surface.

Small volumes of ECPC (especially if elastomeric) may be used along withwire to form a switch, by making temporary contact with at least twowires and shorting them together when the ECPC, mounted to a compliantstructure, is pressed, slid, pulled, etc.

Devices with built-in sensors, antennas, and integrated circuitsproviding processing and memory, as well as batteries orenergy-harvesting devices (e.g., electromagnetic, thermoelectric,capacitive, piezoelectric), may be made with FEAM. Such devices may beable to report on their usage history and structural integrity, forexample, providing notification of the need for service and otherstructural health monitoring data. Devices that can participate in the“internet of things” (TOT) are possible.

Oxygen masks or masks for continuous positive airway pressure (CPAP) maybe produced using FEAM from suitable elastomers, and may incorporatesensors such as strain gauges which measure breathing rate andinhalation/exhalation force, or microphones to detect snoring or pick upvoice communications and commands.

Energy-harvesting devices, or products incorporating such devices, maybe made using FEAM. For example, an elastomeric shoe sole made with FEAMmay incorporate electromagnetic or piezoelectric elements to generateelectricity as the wearer takes steps.

Non-resorbable medical implants may be produced using FEAM from suitablematerials which incorporate sensors and interconnects that measurestress, strain, pH, and other useful parameters.

The ability to create structures from dielectric materials, includingrigid dielectrics such as ceramic or glass, or even (e.g., hightemperature, low-porosity) polymers, along with encapsulated/embeddedwire enables the fabrication and integration into structures ofmonolithically-fabricated vacuum electronic devices such as diodes andtriodes, as well as travelling-wave tubes and other devices useful forcomputation, signal generation, illumination (e.g., incandescent bulbs),etc. In some embodiments, all vacuum devices can be connected to one ormore common manifolds such that they can be evacuated of air afterfabrication and then sealed (at one or multiple points) to make themfunctional. Electrons in vacuum electronic devices can be generated bythermionic emission, by field emission (e.g., from the free ends ofsmall and/or sharpened wires, which may be sharpened electrochemicallyin-situ), etc. All the elements in a conventional vacuum tube, includinggrids, filaments, plates, can be formed using wires that are anchored inthe surrounding tube envelope (which may have a wide variety of shapes,some quite different from a standard vacuum tube) and which form complexshapes within the empty space of the tube.

FIG. 109 depicts a coaxial cable made according to some embodiments andserving as a built-in, high frequency capable and/or noise-insensitivesignal line in a fabricated object. For example, a microwave ormillimeter wave system such as a phased array radar may benefit fromshielded, coaxial signal transmission lines (though coplanar waveguideand other approaches are also achievable in the disclosed process), andspecialized coax-based structures may serve as filters, hybrid couplers,and other microwave/millimeter wave components. In some embodiments,braided shields may be co-deposited with polymer or embedded, but insome embodiments, coaxial structures similar to those shown in FIGS.109(a), 109(b), and 109(c) may be fabricated in-situ. The methods shownin FIGS. 107(a), 107(b), 107(c), 107(d), and 107(e) for laying wireside-by-side can be applied to making the top and bottom sections of thecoax outer conductor/shield (although this can also be made from asingle piece of wide, ribbon-like wire), whereas the center conductorand side sections involve more widely-spaced wires. In FIG. 109(a), onepossible cross section of a coaxial transmission line is shown, in whichthe center conductor is supported by polymer members on either side. Thepolymer is preferably low loss (e.g., tangent loss), such as ZEONEXRS420 made by Zeon Corporation (Chiyoda-ku, Toyko, Japan), polystyrene,liquid crystal polymer, polyethylene, and polycarbonate, which can besolid, foamed, filled with hollow particles (such as hollow glassspheres from Potters Industries) or particles with good dielectricproperties. Similarly, the cross section shown in FIG. 109(b) usesmembers above and below the center conductor (in some embodiments, oneof these members in either version may be eliminated. By contrast, thecross section shown in FIG. 109(c) has no supports; this is intended torepresent a cross section intermediate between cross sections such asthose shown in FIG. 109(a) or 109(b). In other words, to reduce losses,it is best for the space between the center conductor and shield tocontain as little dielectric as possible. Preferably most of the lengthof the coaxial line has a cross section similar to that of FIG. 109(c),but as needed, the other cross sections would be provided to givesupport to the central conductor. In some embodiments, the small gapsbetween wires shown may be larger or smaller than shown, depending onelectromagnetic and process requirements. In some embodiments, wireswould also be provided in the four corners of the cross-section shown inFIGS. 109(a), 109(b), and 109(c). In some embodiments, wires with othercross-sectional shapes such as flat (rectangular), hexagonal, or evenoval or circular, may be used in lieu of the square wire shown, and theoverall cross-sectional shape of the coaxial structure may be of adifferent shape than square as shown. For example, using flat wire, thetop and bottom of the shield can be made with fewer pieces of wire ifthe shield is square, or a low-profile shield can be produced withrectangular overall cross-section. In some embodiments, structures suchas those in FIGS. 109(a), 109(b), and 109(c), but without the centerconductor, can serve as waveguides for high-frequency signals.

Coaxial cables and other structures such as these can serve astransmission lines but also as passive devices including band passfilters and hybrid couplers. They can be built straight, curved, and inserpentine or spiral configurations, for example, leading to compacthigh-frequency systems embedded within structural elements (e.g., thewings or fuselage of an unmanned air vehicle).

Coaxial structures may be incorporated into fabricated objects in someembodiments by a number of methods other than that described in FIGS.109(a), 109(b), and 109(c). For example, the insulation of wire that isflexible and small diameter (e.g., the 2420/42 ultra-flexiblemicrominiature lead wire of Daburn Electronics & Cable (Dover, N.J.) canbe metallized, providing a coaxial structure that can then be printed aswith normal FEAM printing of plain or insulated wire.

FIGS. 110(a), 110(b), 110(c), 110(d), 110(e), 110(f), and 110(g) depicta method used in some embodiments for fabricating coaxial structureswherein the center conductor may be a bare wire (e.g., copper, gold),the dielectric material is co-deposited as the wire is laid,encapsulating it, and the shield is applied using a secondary process(after at least a portion of the object has been fabricated). In theaxial cross-sectional view of FIG. 110(a), a channel has been fabricatedthrough the fabricated object. As shown, the channel has a triangularcross-section wherein two walls are at an angle beta (e.g., greater than45°) sufficient to avoid the need for support material duringfabrication; however, in some embodiment variations, other shapes suchas circular and rectangular may be used, as well as support material(e.g., removable). On the floor of the channel support posts (e.g.,dielectric) have been deposited at intervals as is clear from the radialcross-sectional view of FIG. 110(c). These posts are preferably narrowin the wire axial direction. Above the posts is deposited an elongatedwire encapsulated within co-deposited dielectric, such as a polymer withdesirable high-frequency characteristics (e.g., low tangent loss). Amongthe polymers which may be suitable are thermoplastics such aspolystyrene, liquid crystal polymer, polyethylene, and polycarbonate,and ABS, all of which also can be electroplated and/orelectrolessly-plated. Similar to FIGS. 55(a) and 55(b), the dielectriccan bridge from one post to the other, by virtue of the wire inside.Bridging may be enhanced in some embodiment variations by keeping thewire under slight tension (e.g., feeding it at a linear speed slightlyslower than the nozzle speed) and/or by rapid cooling of the dielectricupon extrusion. If the center conductor in the structure of FIGS.110(a), 110(b), 110(c), 110(d), 110(e), 110(f), and 110(g) is notencapsulated while being co-deposited with the dielectric, but insteadis embedded (e.g., ultrasonically), support material can be depositedunder the bridge to support it during the embedding process, and thenremoved before metallization.

In some embodiment variations, the wire and dielectric may not be in achannel as shown (e.g., the wire and dielectric may be on the surface ofan object); however, a channel will be assumed in this description.After fabrication of the structure shown in FIG. 110(a), the outsidesurface of the dielectric can be metallized. In some embodimentvariations this may be accomplished by a vacuum metallization processsuch as sputtering or evaporation, or a gas phase process, while inother embodiment variations as will now be described, this can beaccomplished by electroless plating. The channel may have apertures (notshown) at particular locations along its length to allow fluids to enterand exit the channel. In some embodiment variations, an electrolessplating bath may be introduced along with other chemicals, as known tothe art of electroless plating, such as cleaners, activators,conditioners, sensitizers, acids, catalysts (e.g., palladium), etchants,and rinses. The plating bath and associated chemicals may deposit avariety of metals, such as copper, nickel, gold, and tin (e.g., forsolderability), various alloys, or a combination of several metal films,one on top of another. For high frequency applications, for example, agold film having a thickness comparable to the skin depth can bebeneficial. The plating bath and associated chemicals (collectively,“liquids”) can be introduced into the channel in some embodimentvariations by immersing the fabricated object, in which case liquids mayenter the channel through apertures and/or the ends of the channel. Insome embodiment variations liquids may be made to flow through thechannels, e.g., driven by a pump. Channels may be interconnected and/orconnected to a manifold which may be built into the object, thusallowing liquids to be introduced into channels and emptied from them insuccession. Once introduced, liquids may reside inside the channels fora certain amount of time, or may be recirculated, as required by themetallization process.

Whatever the particulars of the process, after metallization, thestructure appears as in the axial cross-sectional view of FIG. 110(b),and as in FIG. 110(c). Metal has formed an additional coating on theinner walls of the channel and around the support posts, but moresignificantly, has coated the dielectric surrounding the wire centerconductor. The result is a coaxial structure whose shield is continuousexcept in a few locations in which it interrupted by the support posts.The additional coating of the channel walls can serve to further shieldthe wire serving as coax center conductor. In some embodimentvariations, the dielectric surrounding the wire may not be easilyplatable (e.g., polyethylene, PVC, PTFE), but the dielectric comprisingthe walls of the channel is platable. In such as case, the dielectricsurrounding the wire may be made very thin and the walls of the channelform the coax shield, with air as the primary (very low-loss)dielectric. In some embodiment variations, the wire is uncoated bydielectric, and supported at its ends and/or by regularly-spacedsupports, and metallization of the interior of the channel (e.g., byelectroless plating) generates a shield. Then, the wire, the channelwalls, and whatever fills the channel (e.g., air) together comprise thecoaxial structure. If the wire itself becomes metallized in the process,that is usually acceptable. In some embodiment variations, thedielectric surrounding the wire may be platable but the walls of thechannel are not platable, thus no additional metal coating is generated.

FIG. 110(d) is a 3-D transparent sectional view of the channel beforemetallization, and FIG. 110(e) is a close up 3-D sectional view of thechannel after metallization. FIGS. 110(f) and 110(g) are 3-D sectionalviews similar to FIG. 110(d), but with the side of the channel removedfor clarity. In FIG. 110(f), the structure is shown as-fabricated, whilein FIG. 110(g), the structure is shown after metallization, such as bycopper or gold electroless plating. In some embodiment variations,multiple coaxial structures may be incorporated into a single channeland metallized simultaneously. In some embodiments, no center conductoris provided, and the dielectric shown surrounding the wire in FIGS.110(a), 110(b), 110(c), 110(d), 110(e), 110(f), and 110(g) is puredielectric, which when metallized by a secondary process, yields awaveguide. Alternatively, the channel itself, once its interior surfaceis metallized, can form a waveguide.

In some embodiments, the dielectric, which provided a surface upon whichmetal was deposited, remains in place. However, in other embodiments,the dielectric is removed at least in part. The dielectric, for example,can be a soluble material such as polyvinyl alcohol, polylactic acid,etc.), and dissolution can take place through the ends of the coaxialcable or waveguide, and can be facilitated by incorporating etch holesalong the length of the structure.

In some embodiments, electrolytic plating of coax shields and otherstructures (such as junctions between wires) can be implemented, forexample, by incorporating wires into the fabricated object which are,for the most part, exposed (e.g., supported at intervals by stopping andstarting the flow of polymer while printing). Such wires can serve asanodes for electrolytic plating, and a suitable plating bath can beintroduced (e.g., within a channel) between the anodes and a structureto be plated, serving as a cathode. For example, one or more anodes canbe incorporated into the channels of FIGS. 110(a), 110(b), 110(c),110(d), 110(e), 110(f), and 110(g) so as to electroplate the coaxshield, in some cases, to thicken it after electroless plating. In someembodiments, wires incorporated into objects may serve as electrodeswhich allow, with a suitable bath chemistry, electrochemical machining,polishing, deburring, sharpening, and other processes of metallicstructures such as other wires in the object.

Coaxial structures made according to the processes of FIGS. 110(a),110(b), 110(c), 110(d), 110(e), 110(f), and 110(g), may in general needto be interfaced to connectors, devices (e.g., high-frequency integratedcircuits), etc. Thus a region of the center conductor, e.g., at the endof the structure, must be exposed (i.e., not covered by dielectric or bya metallic shield). A method used in some embodiments to achieve a barecenter conductor involves 1) encapsulating the region to be bare in aremovable (e.g., soluble) and preferably unplatable support material inlieu of normal dielectric material; 2) metallizing (e.g., usingelectroless plating as described above), which if the support materialis not plated, will leave it exposed; and 3) removing the supportmaterial. An alternative method used in some embodiments is to leaveregions of the center conductor uncoated/unencapsulated in dielectric.During the region uncoated in dielectric and proceed with themetallization process. The exposed center conductor may become itselfmetallized, which can increase its thickness, though usually by anegligible amount. The side of the dielectric, however, will likelybecome metallized, potentially forming a short between the shield andcenter conductor. However, the thin coating of metal on this wall can beremoved (e.g., by abrasive blasting).

FIG. 111 is a cross-sectional plan view of a process in some embodimentsfor forming a shielded junction in the form of the letter “T”; however,junctions with other geometries such as that of the letter “L” or “X”may be similarly formed. In FIG. 111(a), two wires have been laid, eachencapsulated by co-deposited dielectric in certain regions. Conductivematerial (e.g., ECPC, solder) has then been applied as in FIG. 111(b) toform an electrical junction between the wires. Then, in FIG. 111(c),additional dielectric has been deposited to fully encapsulate theconductive material and any exposed portion of the wires. Finally, inFIG. 111(d), the structure of FIG. 111(c) has been metallized (e.g., byelectroless plating after the entire object is fabricated), resulting ina continuous outer shield surrounding the joined center conductors.

FIGS. 112(a), 112(b), and 112(c) depict a modified FEAM method in someembodiments in which, in addition to supplying wire (e.g., of roundcross-section) to the extrudate so that the wire is encapsulated byliquid material as printing progresses, at least one narrow strip orfoil of metal is also supplied. FIG. 112(a) is a 3-D view of a nozzleextruding a polymer (e.g., molten thermoplastic), nearby which arelocated two capillaries. The upper feeds wire, while the lower feeds ametal strip. In some embodiment variations, as shown in the 3-D view ofFIG. 112(b), surface tension of the extruded liquid causes the thinstrip, whose width has been carefully selected, to be pulled inwardstoward the extrudate, ultimately wrapping around the extrudate to formthe shield of coax cable, possibly with a small seam (a gap as shown, oroverlap area), as illustrated in the cross-sectional view of FIG.112(c). In some embodiment variations, rather than a single stripwrapping around the extrudate, two or more strips may be provided (e.g.,on either side of the extrudate) which both wrap around the extrudateand together form the shield. In some embodiment variations, rather thanor in addition to relying on fluid forces to deform the strip(s) intothe desired shape(s), at least one mechanism such as guide fingers orforming dies which move along with the nozzle on either side of theextrudate, force the strip to adopt the desired shape.

FIGS. 113(a) and 113(b) depict cross-sectional views of two junctiondesigns in addition to those previously described (e.g., FIGS. 98(a),98(b), 98(c), 98(d), 98(e), and 98(f)), and used in some embodiments.FIG. 113(a) can be seen either as a plan view (for an intra-layerjunction) or an elevation view (for an inter-layer junction) of ajunction wherein the wires extend substantially straight across a cavityin the surrounding dielectric material. As shown, even if the junctionis at the end of a wire, the wire may extend past the cavity so it canbe better anchored in the dielectric. FIG. 113(b) depicts a plan view ofa junction with two wires that are bent approximately 90° within thecavity; these wires may be on the same or different layers. In the caseof both junctions, conductive material has been applied to the wires,shorting them together, but the conductive material, as shown, does notnecessarily make contact with the material forming the cavity walls,floor, or ceiling (if applicable). Thus the conductive material may beapplied or reflowed at a temperature higher than the temperature easilytolerated by the material of the cavity, if care is taken not to makedirect contact with the cavity walls. Moreover, the material need notadhere to the cavity walls, so long as it adheres well to the wires.Also, the junction is somewhat isolated from strains imposed on thecavity walls by the surrounding fabricated object, especially in thecase of the junction in FIG. 113(b). Finally, since the wires in bothjunctions are anchored within two cavity walls, they are less likely todeflect (e.g., if subject to a force while creating the junction, suchas the drag due to ECPC entering the cavity).

As already described above, in addition to forming junctions with ECPC,junctions may be formed with other materials, such as conductive inks,powders, fine wires, and solder (including deposited and reflowed solderballs), or without the addition of other materials, such as by welding.In the cross-sectional elevation views of FIGS. 114(a), 114(b), 114(c),and 114(d), junctions may be formed in some embodiments using solderdelivered to the wires via a heated tube. In FIG. 114(a), a junctionprecursor comprising two wires (preferably tinned) on different layers(e.g., adjacent layers) similar to that of FIG. 113(a) is shown. In someembodiments, the wires may not cross the cavity completely and continueinto the right-hand wall of the cavity as shown, but may terminatewithin the cavity as in FIG. 98(a). In some embodiments, the wires maynot overlap in FIG. 98(b), but may be staggered as in FIG. 98(c). Aheated tube (e.g., borosilicate glass, stainless steel, ceramic) isprovided to deliver molten solder. The tube is filled with solder, or isin communication with a reservoir of solder. The tube can be heated, forexample, by wrapping it with an insulated, resistive heater (e.g.,wraparound heating cord from Omega Engineering, Inc. (Stamford, Conn.).By applying pressure to the solder (e.g., by air or plunger) or reducinga vacuum above, the solder can be made to flow through and out of thetube. In the figure, the solder is entirely within the tube, which maybe beneficial to prevent a solder drop from breaking off inadvertentlydue to motion or vibration. In some embodiment variations, one or twoadditional elements are provided, as shown in FIG. 114(a): a tube thatdelivers flux (e.g., from a reservoir), and a tube or other means forextracting fumes which may be produced during soldering of the joint. Insome embodiment variations, the tubes are at arranged differently, e.g.,at different relative angles. All elements can move together as part ofa soldering head which can be positioned anywhere within a layer of thefabricated object that a junction is required; alternatively theelements can be transported by a printhead in the X/Y plane, and loweredas needed to reach the junction volume.

In FIG. 114(b), the elements have been positioned to partially enter thecavity and flux (if needed) has been caused to flow from the left-handtube onto the wires. In some embodiment variations, rather than beprovided as a drop, flux can be sprayed in atomized form, or pre-mixedwith the solder. In some embodiment variations, the flux can bepre-heated in its reservoir and/or as it flows down the tube, toactivate it. In FIG. 114(c), molten solder has been caused to flow ontothe wires; the fume extractor is also activated if needed. In FIG.114(d), the elements have been removed, breaking off the drop of solder,which remains on the wires, forming a junction.

A similar process can be used in some embodiments to join more than twowires, to join wires within the same layer rather than different layers,to join wires both within the same layer and on different layers, tosolder wire to pads on devices such as integrated circuits and photonicdevices, etc. A similar process may be used to create a joint usingsolder paste, such as Indium5.7LT (Indium Corporation, Utica, N.Y.), alow-temperature, no-clean, lead-free solder paste incorporating eutectic58Bi/42Sn or 57Bi/42Sn/1Ag alloys. In this case, one tube can supply thesolder paste (and in some embodiment variations, the paste can bepre-heated in its reservoir and/or as it flows down the tube, toactivate it), while the other tube can supply air at high temperature(e.g., similar to the ZT-2-MIL Hot AirPencil) to reflow the paste. Asimilar process (possibly without flux or fume extraction) can also beused in some embodiments to deliver inks such as self-drying inks (e.g.,those of Voxel8), photonically-cured inks (e.g., those of NovaCentrix(Austin, Tex.), etc.

In some embodiments, it is desirable to incorporate into a fabricatedobject fibers that are large in cross-sectional height (e.g., largerdiameter). In some embodiments, the thickness of a layer may be variedaccording to the height of the fibers to be encapsulated in the layer.In other embodiments as described in FIGS. 115(a), 115(b), 115(c),115(d), 115(e), 115(f), 116(a), 116(b), 116(c), and 116(d), it ispossible to incorporate a fiber of greater height than the layerthickness. FIGS. 115(a), 115(b), and 115(c) depict in a cross-sectionalelevation view a method of encapsulating a fiber within a trench. InFIG. 115(a), the trench is formed by depositing several layers (asshown, three). In FIG. 115(b), the fiber is laid within the cavity, andin FIG. 115(c), the cavity has been capped. In some embodimentvariations, while the fiber is laid, matrix material (e.g., polymer) canbe deposited around it, as in the standard FEAM process. In otherembodiment variations, after the fiber is laid, matrix material may beintroduced to surround it. The plan views of FIGS. 115(d), 115(e), and115(f) illustrate the steps in FIGS. 115(a) and 115(b) from a differentangle. FIG. 115(d) shows that the trench may have a complex (e.g.,serpentine) shape. To lay fiber into a non-linear trench such as this,it may be delivered by a capillary such as is normally used in FEAM. Thecapillary can be entirely above the top surface of the trench, or can benarrow enough to be inserted at least partially in the trench. Matrixmaterial may be deposited around the fiber continuously, intermittently,or at one or both ends, to retain the fiber in the trench, if required(if the trench is capped, this may not be).

FIGS. 116(a), 116(b), 116(c), and 116(d) depict in cross-sectionalelevation views an alternative approach in some embodiments forincorporating a fiber having a height greater than the local layerthickness. In FIG. 116(a), a substrate has been provided, upon which awire, encapsulated in matrix, has been deposited in FIG. 116(b). In FIG.116(c), other structures on the layers above the substrate have beenformed around the fiber, possibly with a gap between them and the fiberas shown, as it may not be possible to deposit them directly adjacent tothe fiber, protruding above the surface. Finally, in FIG. 116(d), thenext layer has been formed, including if desired, a cap over the fiber.

Fiber may shrink less than matrix material in a fabricated object, suchas when a metal wire is co-printed with a thermoplastic polymer, and theobject allowed to cool. Shrinkage can be due to phase changes, cooling,curing, etc. This differential shrinkage may lead to fibers, especiallythose surrounded by air (or other fluid) which are intended to bestraight but which curve, sag, or buckle as the surrounding matrixcontracts. Conversely, the fiber may shrink more than the matrix, inwhich case, it may break under tensile stress. Several methods may beused in some embodiments to mitigate or control this distortion. Forexample, in some embodiments, the fiber may be given a corrugated (e.g.,serpentine or sinusoidal) shape before laying it. Then, it can be laidunder some tension (e.g., by feeding it at a speed or through a distancethat is less than the nozzle's motion), stretching out the corrugationand straightening the fiber at least partly (though not enough tocompletely plastically deform the fiber). Then, if the matrix shrinksrelative to the fiber, it will simply adopt a more corrugated form,controllably, without buckling or sagging. Or, if the fiber shrinks morethan the matrix, it will simply become less corrugated.

Other methods of reducing differential shrinkage effects include heatingthe wire to increase its axial shrinkage upon cooling, and using matrixmaterials with reduced shrinkage (e.g., containing glass microspheres).

FIGS. 117(a), 117(b), and 117(c) depict an arrangement of fibers whichcan accommodate differential size changes. In FIG. 117(a), the fibersare formed into compliant loops in the region between regions of matrixmaterial where there is no matrix (e.g., the fibers are surrounded byair). A change in the width of the region causes a controlleddeformation of the loop, but no sagging or buckling. In FIGS. 117(b) and117(c), the fiber is formed into a serpentine shape and anchored to thematrix only at certain locations. Considering the shape of the fiber tobe sinusoidal, the fiber is anchored as illustrated in the region of its“zero-crossing points”. However, it may instead, or in addition, beanchored in the region of its “peak” and “trough”. In FIG. 117(b), thefiber is within a trench which allows it some movement relative to thematrix, while in FIG. 117(c); the fiber is on the surface of layer N andanchored by small structures on layer N+1, allowing it even morepotential movement. In some cases, the fiber may undergo a more dramaticsize change than the matrix; in such cases, the methods described aresimilarly applicable.

Other methods of eliminating buckling involve using a wire that can bestretched (e.g., Litz wire, wire that is wound into a helical or doublehelix (with two strands) shape, etc. If such wire is stretched slightlybetween two anchor points, it will simply shorten as the surroundingmaterial shrinks, without buckling.

FIGS. 118(a) and 118(b) depict a multi-nozzle printhead intended in someembodiments to allow FDM and FEAM-based printing with multiple materials(e.g., both structural/model and support materials) and/or multiplenozzle geometries. As depicted, a cylindrical turret is provided, thoughother shapes such as square, hexagonal, and octagonal may be used. Alongthe outer surface are arranged multiple (e.g., four, as shown) nozzles.The turret can rotate, bringing any nozzle to the bottom, such that itsorifice is in a consistent position. In this position, the lower end ofall nozzles may be arranged to be at the same height, however in someembodiment variations, the heights may differ among nozzles. Bybypassing the need for multiple nozzles in different locations inconventional FDM machines, this approach avoids needing to know theexact X and Y offset distances between nozzles, allows parts larger in Xand Y to be built without increasing the travel range(s) of the X and/orY stages, and avoids the potential for collision between an inactivenozzle and the fabricated layer. It further allows inactive nozzles tobe serviced at a convenient location (e.g., wiping excess material fromthem, purging them to manage a clog). Finally, in the case of a FEAMsystem in which the platform rotates as in FIG. 42, all nozzles can beprecisely aligned with the theta axis, which allows all of them to beused when encapsulating fiber.

In some embodiment variations, the nozzle orifices have different sizesand/or shapes, as may be useful, for example, when a fine nozzle isneeded to produce small features, while a coarse, larger diameter nozzleis used, for example, to rapidly deposit material over large areas suchas the interior of a layer. If all nozzles are used to deposit the samematerial, they may be fed in some embodiment variations using a singlefilament, e.g., entering the side of the turret near its center ofrotation. Or, in other embodiment variations using a common hopper andextruder which supplies pellets, and one or more extruders may in someembodiment variations be built into the turret.

In some embodiment variations, different materials are supplied todifferent nozzles, as shown in the figures. In the elevation andcross-sectional views of FIG. 118(a), each filament may enter the sideof the turret through an inlet, advanced by feed rollers, and be meltedin a right-angle liquifier in which the molten material flows through a90° turn (in some embodiment variations, other angles may be used), suchthat the molten polymer (or other material) can issue through thenozzle.

In some embodiment variations, the turret can be rotated so that thenozzle axis is not vertical as shown in FIG. 118(a), but is at anon-zero angle “A” from the vertical Z axis. At such an angle, themachine can be used to print layers at an angle A from the horizontal,e.g., which may be desirable to minimize stairsteps. Such printing ingeneral requires coordinated movements of the platform or nozzle in Z aswell as X and Y. In some embodiments, the turret axis parallel to the Zaxis, not horizontal as shown in FIG. 118(a), and the axis of thenozzles is also parallel to Z. In this configuration, the liquifiers mayhave a straight instead of a right-angle design.

If the turret were to rotate continuously in one direction to switchbetween nozzles, filaments entering it may become twisted. To avoidover-twisting, in some embodiment variations, the amount of rotation ismonitored and the turret reversed as needed. In some embodimentvariations, coiled filaments may be arranged concentric with the turret(i.e., multiple coils can be distributed axially along the turretrotation axis), so that as the turret rotates, the coil rotates as well.In such an arrangement, new filament may be pulled from either theexterior of the coil (e.g., if on a spool) or from its center (e.g., ifthere is no spool).

FIG. 118(b) depicts another embodiment variation in which the filamententers the turret neither parallel to the turret axis of rotation, norparallel to Z, but rather, through a hole on the (e.g., cylindrical)wall of the turret, and then arcs toward the liquifier. However, caremust be taken to prevent excessive filament twisting in thisconfiguration.

In some embodiment variations, a single motor may be used to advance thefeed rollers of the active nozzle, so that a motor is not required forall nozzles. In some embodiments, the axis of the turret may be oblique,as with the turrets on multi-objective microscopes, with nozzlesoriented such that the active nozzle is always parallel to the Z axis.In the case of multiple nozzles delivering the same material, the turretmay include only nozzles and not feed rollers and liquifiers, both ofwhich remain fixed, and a single filament (e.g., entering verticallythrough the rollers) may be provided. Thus, the nozzle geometry can berapidly changed. In some embodiment variations, an extruder such as thescrew extruder of FIG. 49 may be used in combination with a turretsystem. Multiple such extruders may be housed within the turret, withpolymer pellets fed to them through tubing feeding into the inlets, inlieu of filament. The tubing may be vibrated and/or air flow or pressuremay be used to help transport the pellets into the turret.

In some embodiments, it is desirable to incorporate bare orminimally-supported fiber in a fabricated object. If the fiber isstraight (i.e., the shape it typically has when delivered through thecapillary), it may be sufficient to anchor it to the object at bothends. However, if the desired shape is curved as with the fiber in theplan view of FIG. 119(a), for example, it must be curved into the shape,as well as being anchored. FIG. 119(b) depicts in plan view a fiberwhich is laid using FEAM while being encapsulated in a removable supportmaterial. The support material, which may be anchored to structures onthe same or underlying layer, thus captures the fiber and forces it tobe laid in the desired form. Removal of the support material then freesthe fiber, resulting (if the fiber is very ductile) in a fiber shapedsimilarly to that of FIG. 119(a). If the fiber is less ductile andretained residual stress, then after removal of the support material, itwill spring back into a new configuration. For such fibers, the initialshape of the fiber when constrained by support material can be designedto compensate for the springback, so that the desired shape is achieved.

In some embodiments, springback and temporary constraint of non-ductilefibers may be exploited so as to store mechanical energy in a fabricatedobject, which can later be released to do work or distort the fabricatedobject in desirable ways. For example, a coil spring may be fabricatedfrom a relatively high yield wire (e.g., thin music wire), encapsulatedby soluble support material. Upon dissolution, the spring will unwindpartially; this motion or the forces it produces on surrounding elementscan be used to advantage, e.g., to produce motion in a fabricatedobject, or to reduce the clearance between two components in a printedassembly. For example, a wind-up toy may incorporate gears and a springthat is built already wound-up. Removal of the support material can thenrelease the spring. Wire that is laid under tension or torsional strain,as well as bending strain, can deform an object, such as one made atleast in part from an flexible material, into a shape that might noteasily be fabricated (e.g., one with surfaces which if built at thedesired orientation would exhibit stairsteps, so instead they are builthorizontally or vertically, and rotated into position automatically). Toreliably encapsulate in a deformed state a wire that is relativelystiff, in some embodiment variations cooling of the extrudate may beused, and/or, the FEAM process may process more slowly than usual. Insome embodiments, rather than support material per se, fibers can betemporarily constrained by a restraining material that can be melted,softened, or dissolved, allowing the fiber to reconfigure. In the caseof a material that is melted (e.g., a wax) or softened, the fiberitself, or a nearby fiber, may be used to provide the heat (throughresistive (Joule) heating) needed to melt or soften the material. Insome embodiments, energy may be stored in elastomer structures as wellas, or in lieu of storing it in encapsulated fibers.

To facilitate removal, support material in some embodiment variations isnot continuous along the fiber, but instead is distributed in smallregions such as in FIG. 119(c).

FIGS. 120(a), 120(b), and 120(c) depict a variable-width extruder nozzleused in some embodiments for extruding thermoplastics, thermosets, andother materials. The nozzle has a variable diameter orifice, and is ableto produce a variable-width extrudate. The nozzle, similar in somerespects to a Touhy-Borst device used in medical equipment, comprises aninternal sliding tube, an external tube provided with a ledge at itsbottom end, and an elastomeric ring. The ledge is perforated with acentral hole whose diameter is at least as large as the largest orificerequired. The elastomeric ring has an inside diameter which is at leastas large as the largest orifice required. The ring is sandwiched betweenthe lower end of the internal tube and the ledge as in FIG. 120(a). Byapply a force to the tube, the ring is compressed, causing its insidediameter, which forms an orifice, to be reduced. Material inside thetubes, if pressurized, is forced through the orifice, forming anextrudate whose diameter is determined by the compression of the ring.In FIG. 120(a), the ring is compressed little if at all, while in FIG.120(b), is compressed far more, reducing the orifice size. The orificeof such an extruder nozzle can be rapidly varied in size while an objectis being fabricated, either continuously, to create tapered extrudates,or in steps. For example, a small orifice can be used to depositmaterial for small features, while a larger orifice may be used torapidly deposit material over large areas. The ledge is preferably asthin as possible, so that the orifice can be as close to the layersurface as possible. In some embodiment variations, the ring and ledgemay be conical in shape, as in FIG. 120(c), with the ring preferablyprotruding through the ledge, such that there is no opportunity for theledge to disturb the extrudate. In some embodiment variations, the ringmay be compressed radially vs. axially, such as by a 3-4 jaw chuck orcollet known to the art of machine tools, or by providing it with atapered outside surface which is larger toward the bottom, and sliding aring along it to vary the radial compression. For use withthermoplastics and other materials at elevated temperature, the tubesare preferably made from metal, and the elastomer is preferably ahigh-temperature material such as silicone.

FIGS. 121(a), 121(b), 121(c), 121(d), and 121(e) are elevationcross-sectional views depicting a method for building structures in someembodiments using additive manufacturing, in which the strength of thefabricated object is improved along the Z-axis and in the X/Y plane. Thegeometry of the interlayer joint obtained with this method hassimilarities with tongue and groove joints used in woodworking. In FIG.121(a), material has been deposited on Layer N so as to leave one ormore grooves within a single extrudate, or in a group of adjacentextrudates. In FIG. 121(b), material has been deposited on Layer N+1over the material on Layer N. A portion of the material deposited onLayer N+1 forms a tongue which enters into the groove on Layer N,filling it in. The surface area at the interface between Layers N andN+1 is greater due to the tongue and groove than in the case of atypical planar interface, thus increasing adhesion between the layerswhen subject to tensile forces. Moreover, because of the mechanicalinterlocking provided, a shear force such as that shown in FIG. 121(b)is less likely to cause delamination between the layers. In FIG. 121(c),additional layers have been added, and in FIG. 121(d), a small amount ofmaterial has been added to the groove on Layer N+3—an option if LayerN+3 is the topmost layer in this region of the object—forming an insertthat smooths the upper surface.

The groove in FIG. 121(a) may be produced by a nozzle having a shapesimilar to that shown in the 3-D view of FIG. 121(e). A boss havingapproximately the width of the desired groove projects from the bottomsurface of the nozzle. When the nozzle moves relative to the buildplatform in the direction shown, the boss forms the extrudate into ashape having a groove. The nozzle (or the fabricated object) can berotated according to the nozzle trajectory, such that the boss remainsmore or less tangent to the path. Once the groove of FIG. 121(a) isformed, entry of material into the groove on Layer N+1 may occurnaturally as the result of the material on Layer N+1 being flowable.However, if a nozzle such as that in FIG. 121(e) is used to depositmaterial on Layer N+1, the boss, while forming the groove on that layer,will also tend to push material down into the groove on Layer N.

In some embodiment variations, the boss is given an undercut shape(e.g., wider at the bottom than at the top, or shaped like an invertedletter “T”). The resulting groove in the extrudate of Layer N is thusalso undercut, and material applied on Layer N+1 entering the groovewill be mechanical interlocked once solidified. Despite the undercutgeometry, removal of such a boss from the extrudate (e.g., when jumpingto a new location on the layer, or on another layer) is easilyaccomplished by selecting a location along the toolpath where theundercut can be disrupted with negligible effect, and simply pulling thenozzle through the material while the latter is in a flowable state(e.g., melted).

In some embodiments, grooves formed in extrudates may be used toincrease the bond strength between extrudates within the same layer. Forexample, by incorporating a projection on the nozzle of FIG. 121(e)having a cross-sectional shape similar to the letter “L” (in lieu of the“I”, or straight shape shown), and locating the projection to one sideof the orifice centerline, a groove can be formed in the sidewall of theextrudate, instead of at the top (however, both types of grooves can beused). As with the upper boss, an undercut shape can be provided. Forexample, the groove can be formed in the side pointing in the directionof positive X, if the extrudate runs parallel to the Y axis). Extrudatethen deposited on the opposite side (pointing in the direction ofnegative X) will then tend to flow into the groove and increase thebonding between the neighboring extrudates. An entire series ofside-by-side extrudates may thus be formed, with the groove consistentlyon one side; however, in some embodiment variations, the side may vary.

FIGS. 122, 123, and 124 depict novel coil designs that can beadvantageous in some embodiments in the context of the FEAM process.FIG. 122 depicts a 3-D view of a single-layer spiral coil similar insome respects to one of the coils in FIGS. 11(a) and 11(b), but having a“quantized” radius. In other words, unlike a typical spiral in which theradius changes continuously with angle, the radius of the spiral in FIG.122 is constant for most angles, and changes suddenly at a particularangle. This design can be implemented in a multi-layer version as well.

FIG. 123 is a 3-D view of a multi-layer spiral coil in some embodimentsin which the spiral wires on each layer are connected electrically inseries with one another, in which current can flow consistentlycounterclockwise as seen from the top or clockwise (as shown) throughall spirals, in which the connections between spirals are made using aconductive material such as ECPC or solder (vs. continuous wire), andmost significantly, in which the spiral on each layer is produced bylaying wire from the inside to the outside, i.e., with increasingradius. It can be easier in the FEAM process to produce a spiral shapein which the radius only increases, as there is no potential forinterference, especially with small diameter coils, between a portion ofthe spiral already formed and the capillary. To achieve this, the spiralon Layer N is formed with increasing radius in a counterclockwisedirection, that on Layer N+1 is formed with increasing radius in aclockwise direction, that on Layer N+2 is formed with increasing radiusin a counterclockwise direction, and that on Layer N+3 is formed withincreasing radius in a clockwise direction, etc. Conductive material,forming a (Z-axis) interlayer junction or via, connects the inner endsof the wires on Layers N and N+1, and the inner ends of the wires onLayers N+2 and N+3. Conductive material also connects the outer ends ofthe wires on Layers N+1 and N+2, and the outer ends of the wires onLayers N+3 and N+4 (not shown), and so forth. In some embodimentvariations, all inner ends of the spirals are connected together, aswell as all other ends, thus connecting all spirals electrically inparallel. The spacing of the layers and therefore, the length of thejunctions, is not necessarily to scale and is exaggerated for clarity;typically spirals are fabricated on neighboring layers, without layersthat are “blank” other than the junction. In some embodiments, spiralwire shapes (e.g., for coils) are preferably made polygonal (e.g.,square) so that potential interference between the capillary anddeposited material only occurs a few times each layer, and the capillarycan be temporarily retracted upward to avoid this interference.

The 3-D view of FIG. 124 depicts a two-layer coil (or two layers of ataller coil) in some embodiments comprising spirals on adjacent layerswhich are formed counterclockwise as seen from above. As with the coilof FIG. 123, the wire spirals can always be generated by starting withsmaller and moving to larger radii. However, here the wire can becontinuous: the wire is directed approximately radially inwards andupwards toward the inner portion of the spiral on the next higher layer,connecting the spirals in series. Alternatively in some embodimentvariations, the inner ends can be connected together, and the outer endscan be connected together, so that the spirals wired electrically inparallel.

Coils built in layers such as those in FIG. 123 have several uniquebenefits over coils conventionally made (i.e., wound on a mandrel). Forexample, each layer can have a different number of spiral turns and/or adifferent pitch (along the coil access), e.g., by changing the layerthickness and/or omitting spirals on selected “skipped” layers. Thecomposition, shape, and size of wire can also vary from layer to layeras can the shape of the wire loop or spiral (e.g., on Layer N this canbe hexagonal, while on Layer N+1 it can be octagonal, or hexagonal witha different orientation of the facets. Thus for example, a coil having across-section that twists along the axis can be provided; such a coil ifused in a solenoid may provide rotation of the plunger as well astranslation, especially if the pitch of the twist is relatively large.Thus, coils which generate gradients (e.g., axial) in magnetic field canreadily be printed, and in some embodiments undesirable gradients whichexist in conventionally-produced coils can be mitigated. In someembodiments involving solenoid actuators, for example, by varying thewire pitch, size, type, layer thickness, etc. axially, an actuator witha more linear force curve (force vs. displacement) can be produced thanis typically possible with a conventionally-wound solenoid coil. Sincethe wire in a FEAM-produced coil is accessible at least once per layer,producing coils which are tapped at nearly-arbitrary locations (e.g.,for transformers) is possible. The dielectric material can be chosenfrom a wide variety of materials, and can be porous or transparent,allowing fluids or light to penetrate the coil windings. Byco-depositing wire and tubing in the same or nearby extrudates, or byusing a dielectric with interconnected pores, coolant can be introducedadjacent to the windings, thus allowing them to operate at highercurrents than normal. Along with the wire in an extrudate, a fiber canbe incorporated made from a fugitive/sacrificial/dissolvable material(this applies in general, not just to coils). Once this is removed, theresulting channel can be used for fluid cooling of the coil windings.Channels between wire-containing extrudates can also be printedin-place, providing fluid conduits without the need to encapsulatetubing. Coils (and other shapes) made using resorbable dielectrics canbe used in implanted devices for such purposes as telemetry orthrough-skin charging, or as neurostimulation or recording electrodes;even if such coils have many turns, once the dielectric is resorbed andreplaced by ingrown tissue, they can be very flexible and virtuallymatched in elastic modulus to the surrounding tissue. Moreover, coilsand other shapes can have very high surface area, a useful feature whenserving as electrodes. Also, since the coils are not wound on a mandrel,they can have a wide range of cross-sectional shapes, including shapessuch as stars which have concave as well as convex regions.

The 3-D view of FIG. 125 depicts a method for building structures fromwire in some embodiments that is similar to that of FIGS. 107(a),107(b), 107(c), 107(d), and 107(e), but in which individual wires (orother fibers) may be welded to one another, either as they are laid, orafterwards in a separate process. In the example shown in the figure,flat (i.e., rectangular) wires are formed into a group in which there islittle or no space between the wires along the Z axis, and a small gapbetween the wires along the Y axis, thus mimicking the effect oflaminations often found in soft magnetic structures to reduce eddycurrents. The vertical plane of the laminations shown is suitable foruse with coils whose axis is parallel to the Z axis, since the eddycurrents would normally circulate in the X/Y plane. The wire thicknessalong the Z axis is in some embodiment variations set equal to the layerthickness.

In FIG. 125, wire is introduced from the left, negative X direction(e.g., through a capillary, not shown) under a nozzle moving relative tothe fabricated object in the negative X direction, while a dielectricmaterial (also not shown) is extruded through the nozzle. In someembodiment variations the nozzle may be furnished with a guide as inFIGS. 107(a), 107(b), 107(c), 107(d), and 107(e). Also provided are twoelectrodes which contact the wire being laid in two locations a shortdistance apart. In some embodiment variations, the electrodes areslightly narrower than the wire along the Y axis and are centered on thewire being laid so as to only contact that wire, and not adjacentwire(s). The electrodes in some embodiment variations move along withthe nozzle at the same speed (e.g., they may be fixed to the printhead).Continuous or pulsed current (the latter producing a series of spotwelds) is passed from one electrode to another using a single-sided,serial, resistance welding configuration known to the art, so thatcurrent passes not just through the upper wire, but also through thewire beneath it, welding the two together. Such welding may achieveimproved bonding of the upper wire to other wires compared with theapplication of dielectric alone, and can serve to reduce the gap betweenwires along the Z axis. The latter is desirable to increase thevolumetric percentage of metal and in some soft magnetic structures, forexample, or for fabricating conductors such as vertical capacitor platesextending along the Z axis across multiple layers. In some cases, only alight weld is needed to achieve the desired functionality.

In some embodiment variations, the electrodes are located downstream ofthe nozzle as shown, such that the nozzle first applies dielectric tothe wire and a short time later, the wires are welded. In otherembodiment variations, the electrodes are located upstream of thenozzle, such that the wires are first welded, and then dielectric entersthe gaps between wires parallel to the X axis. The latter may bepreferred in that the top of the wire is less likely to be contaminatedby dielectric material which may interfere with good electrical contactby the electrodes.

In some embodiment variations, similar welding approaches may be used toweld wires in the same layer (i.e., intra-layer) to one another in lieuof or in addition to the interlayer welding already described.Intra-layer welding can be useful, for example, in fabricating groundplanes, capacitors, and patch antennas, or to achieve laminations whichare horizontal instead of vertical. In this case, one electrode wouldcontact one wire on the current layer, and the other electrode wouldcontact an adjacent wire, and the wires would be in contact, without agap.

If the path of the nozzle motion and wire is not straight, theelectrodes in some embodiment variations rotate around the verticalnozzle axis along with the capillary (or the fabricated object mayrotate) so as to remain always on the wire being welded, either upstreamor downstream of the nozzle. In some embodiment variations, in lieu ofrotation the electrodes may take the form of two concentric rings at anangle to the X/Y plane so as to contact one or a small group of wires ata time; the angle can be changed according to the nozzle trajectory soas to maintain contact with the intended wire.

In some embodiment variations, more than two electrodes may be provided.In some embodiments, electrodes may contact wires on more than a singlelayer at a time. In some embodiment variations, electrodes may beconfigured so as to produce interlayer and intra-layer weldssimultaneously.

In some embodiments, in lieu of using electrodes for resistive welding,a spinning pin may be deployed from the printhead which can weld wires(e.g., adjacent wires) using friction stir welding methods known to theart. In some embodiment variations, in lieu of resistance welding,ultrasonic welding may be used. In general, it may be preferred to weldin an area uncontaminated by matrix material, and then apply it asneeded.

FIGS. 126-128 are sequences of cross-sectional elevation views depictingprocesses used in some embodiments for integrating electrical devicessuch as semiconductor die (e.g., a microcontroller, optoelectronicdevice, memory chip, digital to analog converter), MEMS devices,transducers, sensors, discrete electronic devices, or other devices intofabricated objects, and providing an electrical interface to wireswithin the object. The inserted devices may be bare or packaged (e.g., asurface mount package such as a TQFP package), the latter typicallyproviding a larger pad pitch and improved ruggedness, but occupying morespace.

In FIG. 126(a), at least two layers of dielectric material have beenfabricated, producing a cavity in which the device can be placed. Insome embodiment variations, at least the bottom of the cavity is formedfrom a dielectric with high thermal conductivity (e.g., a polymercomposite containing boron nitride powder, or copper powder at aconcentration below percolation) to provide enhanced heat dissipationfor the device. In some embodiment variations, the bottom canincorporate ECPC, metal wires, trapped regions of liquid metals such aseutectic Ga—In, phase-change materials (e.g., incorporated into heatpipes), etc. In some embodiments variations, the thermally-conductivematerial is elastomeric, so as to make better thermal contact with thebottom of device, filling in small irregularities in its surface. Thethermally-conductive region may conduct heat to the surface of theobject, to a heat sink, etc., in order to dissipate heat from thedevice.

In FIG. 126(b), the device has been placed in the cavity with its pads(which in some embodiment variations may include bumps, studs, or otherprojections) facing upwards using mechanical tweezers, forceps, vacuumtweezers, an electromagnet, etc. in some embodiment variations, thedevice may be bonded to the underlying or surrounding material, e.g.,such as by use of an adhesive, or reflowing the material. Preferably theunderside of the device is relatively flat and smooth so as to make goodcontact with the bottom of the cavity, but a thermal interface materialsuch as the TPLI™ 200 Series gap filler from Laird Technologies, Inc.(London, U.K.) can be pre-applied to the device or to the cavity bottomto reduce thermal contact resistance if needed. In FIG. 126(c), anadditional layer has been deposited which includes wires with bare endswhich are to interconnect with the device; the wires are arranged tooverlap and possibly touch the pads on the object as shown. In FIG.126(d), a delivery tube containing conductive material has beenpositioned above a wire and pad. In some embodiment variations, the tubecontains molten solder (as shown and assumed here), while in otherembodiment variations, it may contain ECPC, conductive ink,photonically-cured ink, solder paste, etc. Examples of solders includeSn—Pb and low-temperature lead-free solders such as In52-Sn48 (Indalloy1E), Bi58-Sn42 (Indalloy 281), and In97 Ag3 (Indalloy 290), all made byIndium Corporation. In FIG. 126(e), molten solder has been depositedonto the pad and wire, forming a junction or joint between them. Inembodiment variations in which solder paste has been applied by thetube, it may be reflowed individually at this time using a hot air jet,spot or flood infrared light, or laser, for example, or multiplejunctions may be formed with solder paste and then reflowed in series orparallel (e.g., using at least one air jet or laser beam) before theyare covered with other material, or if the entire fabricated object cantolerate the reflow temperature, the object may be placed in an ovenafter fabrication to reflow the solder paste. In some embodimentvariations, the tube may deliver solid or powdered solder to the jointand a laser or hot air jet used to melt it onto the pad and wire.

In FIG. 126(f), the tube has been moved (e.g., after lifting it andtranslating it horizontally) away from the first pad and has made asimilar junction on another pad and wire. After all junctions are soformed, additional thermally-conductive material may be deposited abovethe device in some embodiment variations (not shown) and, assuming thedevice should not be exposed on its upper surface, the fabricationprocess can been continued with at least one additional layer added. InFIG. 126(g), a layer of dielectric has been deposited over the devicecontaining a grid of wires which support it as in FIGS. 55(a) and 55(b),forming a closed space. In some embodiment variations, cooling of theextruded dielectric, if a thermoplastic, may be used in addition to, orin lieu of, the wires. In some embodiment variations, a grid of wiresabove the device, and optionally below the device, may provideelectrical shielding of the device. In some embodiment variations inwhich additional thermally-conductive material is not added above thedevice, dielectric applied on the next layer is allowed to directlycontact the device. FIG. 126(g′) depicts an alternative approach toforming a closed space above the device, in which a pyramidal orprism-shaped cavity is formed by building up material in multiple layerssuch that the sides of the cavity are at an angle beta (e.g., >45°) thatallows the material to be self-supporting (i.e., without the use ofsupports). In some embodiment variations, rather than use solder orother conductive material to create a junction between the pad and wire,the geometry can be such (e.g., the cavity can be shallower) that thewire shown in FIG. 126(c) is in direct contact with the pad and a laserused to weld the wire directly to the pad.

FIGS. 127(a), 127(b), 127(c), and 127(d) depict a method used in someembodiments for integrating devices like those discussed in conjunctionwith FIGS. 126(a), 126(b), 126(c), 126(d), 126(e), 126(f), 126(g), and126(g′) (or 58(a), 58(b), 58(c), 59(a), 59(b), and 59(c)) in which thedevice is provided with solder bumps on its pads, or alternatively,solder paste. Solder bumps can be produced as known to the art bywafer-scale bumping processes, for example. In FIG. 127(a), a cavity hasbeen created as in FIG. 126(a), and in FIG. 127(b), the device has beenplaced with its bumps facing upwards. Next, in FIG. 127(c), anadditional layer has been deposited which includes wires with bare endsarranged to contact the bumps on the device. Then, in FIG. 127(d), thesolder is reflowed. In some embodiment variations this is achieved by atube delivering hot gas (e.g., air) as shown, while in other embodimentvariations it may be achieved by laser, spot or flood infrared light, byheating the entire object (e.g., after fabrication), etc. Following thisstep, if desired thermally-conductive material may be deposited on thetop surface of the device and/or the device may be closed off usingmethods similar to those shown in FIG. 126(g) or 126(g′). In someembodiment variations, in lieu of solder, ECPC or an electricallyconductive adhesive may be used. This may be a thermoplastic, in whichcase it may be reflowed as described for solder. If a thermoset, it maybe cured thermally or using light (e.g., ultraviolet) to complete thejunction.

In described with reference to FIGS. 128(a), 128(b), and 128(c), deviceswith their electrical pads on a vertical surface instead of a horizontalsurface (as described above) can be integrated with fabricated objects.In FIG. 128(a), a slot has been fabricated in a region of the object,and the bare ends of wires (e.g., in a 2-D array) protrude into the slota short distance (enough to deform against the pads to make goodcontact, but not enough to short pads together, etc.) The wires arepreferably of a relatively hard and high yield metal such as nickel orberyllium-copper so they can provide a reasonable contact force againstthe device pads (or in some embodiment variations, balls, studs, orother interconnect structure) when the device is inserted, andpreferably scratch or “scrub” the oxide off the device pads as thedevice is inserted; however, softer and lower-yield materials such aspure copper may be used. In some embodiment variations, at least theends of the wires may be coated with gold, to avoid oxide formation.When wires chosen for their properties as contacts are used, they may bejoined to other wires (e.g., pure copper, chosen for its electricalconductivity) elsewhere in the fabricated object using ECPC, etc. Thewires are spaced vertically (not necessarily every layer as shown) so asto match the pitch of the pads to be interfaced.

In FIG. 128(b), the device, held by gripper, vacuum tweezers, etc.(e.g., along its edges as shown) is lowered into the slot with its padsfacing the protruding wires; the slot can be made wide enough in thedirection perpendicular to the drawing plane to provide clearance forthe grippers. Insertion can be during fabrication of the object, orafter it has been fully fabricated (i.e., all layers deposited). As thedevice is inserted, the wires are deformed by contact with the devicepads, and once the device has been fully inserted as in FIG. 128(c),they remain deformed and in electrical contact with the pads, withoutthe need for solder or any other extraneous material. In some embodimentvariations, between the wires on the left-hand wall of the slot,dielectric material forming standoffs may be provided to preventexcessive deformation of the wires, especially if the right-hand wall isan elastomer as described below that forces the device against theopposite wall. At this time, unless the device is intended to beremovable or interchangeable (e.g., a secure digital card, a battery),the device can be retained in place and protected from the environmentby depositing a layer of dielectric over it, for example, in which casethe depth of the slot is preferably designed to match the height of thedevice, as shown. Devices may in some embodiment variations be retainedand protected by depositing an underfill material between the device andthe left-hand wall of the slot (or everywhere inside the slot), applyinga blob of encapsulation/potting material (e.g., UV-cured epoxy) over theslot, printing another layer over the top of the devices, etc.

In some embodiment variations, the right-hand wall of the slot iscomprised of thermally-conductive material, so that heat from the devicecan be dissipated. In some embodiment variations, the right-hand wall iscomprised of an elastomer or an expanding material that providesincreased contact force against the wires. In some embodimentvariations, wires protrude from more than one wall of the slot; forexample, a slot intended to accommodate a battery such as a button cellwould have at least one wire (more than one for contact redundancy)protruding from both the left and right walls.

In addition to integrated circuits, optoelectronic devices such as LEDs,MEMS devices, transducers, and sensors, all of which can be bare die orpackaged for surface mounting, and batteries, discrete electroniccomponents having leads such as packaged integrated circuits,capacitors, inductors, resistors, transducers, and switches can beinterconnected to wires using this method, by providing slots or holesof whatever shape is required into which device leads can be inserted.If the lead is large enough, multiple wires may be used (e.g., onmultiple layers) to provide redundant contacts to the leads. Inaddition, slots and holes may serve as connectors (permanent orremovable) for inserted objects. For example, a slot with protrudingwires may serve as an edge connector that makes contact with traces on aprinted circuit board, or interface with a row of pins attached to aribbon cable. A round hole with protruding wires can serve as a jack,socket, outlet, or other female connector, interfacing to a phone plug,mini phone plug, RJ45 connector, BNC connector, AC plug, etc. In someembodiments, the slots are not vertical with respect to the Z, or layerstacking axis of the fabricated object, but at other angles. In someembodiments, the sides of the slot or hole need not be parallel and maybe curved (e.g., a 3-D cavity of complex shape). In some embodiments,the tips of each wire protruding into the slot/hole/cavity may be coatedwith solder (e.g., low melting point solder) or solder paste, or thepads of the device may be coated with solder (e.g., bumped) so thatafter device insertion (e.g., after all layers are built), the objectcan be heated (e.g., in an oven at a temperature that does not disturbor damage it, but causes the solder to reflow, establishing a veryreliable junction between the inserted device pad, lead, or surface, andthe wire.

In the case of integrating high-frequency devices operating for exampleat RF, microwave, and millimeter wave frequencies using methods such asthose described in FIGS. 58(a), 58(b), 58(c), 59(a), 59(b), and 59(c),and 126(a), 126(b), 126(c), 126(d), 126(e), 126(f), 126(g), 126(g′),127(a), 127(b), 127(c), 127(d), 128(a), 128(b), and 128(c), theinterconnects may be coaxial elements such as those in FIGS. 109(a),109(b), 109(c), 110(a), 110(b), 110(c), 110(d), 110(e), 110(f), 110(g),111(a), 111(b), 111(c), and 111(d). In that case, the cavity, slot,hole, etc. surrounding the device may preferably be shielded (e.g., bymetallizing its surfaces) and may be made electrically continuous withthe coax shield(s), e.g., by using a conductive material like ECPC,solder, etc., by using electroless deposition to metallize thecavity/slot/hole along with the coax shield, etc. In general, FEAM mayin some embodiments be used to produce PCBs and other interconnectsubstrates and structures (collectively, “electronic packages”) that areconventionally planar, or 3-D (with components at multiple levels and/ororientations), and which may be rigid or flexible. Componentsaccommodated by such electronic packages may be designed with leads forthrough-hole connection, or pads, bumps, etc. for surface mounting, anda single electronic package may accommodate more than one type ofcomponent. Depending on the method used to create junctions betweeninserted components and wires within the electronic package, the matrixdielectric may be capable of high temperature (e.g., PEEK (e.g.,thermosets (e.g., or thermally or UV-cured) silicone (for flexibleelectronic packages), epoxy). If solder or solder paste is used, thismay be deposited manually or through an automated system (e.g., adispenser on the FEAM machine producing the electronic package) intocavities (e.g., blind cavities) in the electronic package which are toreceive the leads of components with lead, or deposited at or near thesurfaces of the electronic package, to interface with surface mountcomponents. With this material deposited, the electronic package may bepopulated with components, for example, by heating it (e.g., on ahotplate) while components are inserted (manually or by automatedequipment). Electronic packages can also designed with acceptablerobustness (especially if encapsulation and/or underfill is used) inwhich wire contacts the component leads (or in some embodiments, pads,balls, etc.) as described with respect to FIGS. 128(a), 128(b), and128(c), without the need for solder, solder paste, etc., and suchelectronic packages can be populated rapidly by merely insertingcomponents.

In some embodiments, electronic packages which use a soft/elastomericand/or reflowable conductive material such as ECPC may be produced. Withsuch electronic packages, component leads, pads, etc. can be pushed intothe conductive material (while heating the electronic package generally,or locally heating the conductive material and/or lead/pad ifnecessary). For example, the leads of packaged integrated circuits(e.g., dual in-line packaged), resistors, capacitors, inductors,transducers, sensors, switches, headers, and other components oftenfound on PCBs can be simply pushed into soft TPE-based ECPC regions thatare accessible on the electronic package, allowing very rapid populatingof the electronic package after fabrication using FEAM.

FIGS. 129-133 depict fluidic actuators and related devices which may befabricated from elastomeric material, in some cases in conjunction withreinforcing fibers using the FEAM process. FIGS. 129(a) and 129(b) are3-D sectional views of two bellows-like actuators which may be builtwithout supports if desired, since the angle of their walls is greaterthan the value beta (e.g., 45°). Both have fluid inlet ports at thebottom, anti-expansion rings which are thicker than the walls to resistradial expansion when the device is pressurized, and pointed topsgreater than the angle theta. The device in FIG. 129(a) is axiallysymmetric and when pressurized with liquid or gas, will elongate in themanner of a standard bellows. The device in FIG. 129(b), however, has avertical stiffener, or “spine” on one side, which may be internal asshown, external, or partially internal and external. As a result, itcannot expand substantially in the region of the stiffener, and thus notelongate substantially. Expansion of the remaining structure howevercauses it to bend in the direction of the stiffener, thus its mode ofactuation is bending vs. elongation.

FIGS. 130(a) and 130(b) are 3-D sectional views of bellows which mayhave walls at angles lower than theta, and which would then requiresupports, as shown. In some embodiments the supports may be soluble(e.g., if made from polyvinyl alcohol) while in other embodiments, theyare made of the same material (i.e., an elastomer such as a TPE), andthe supports can be cut off after fabrication. In FIG. 130(a), thesupports for the bellows are internal, while in FIG. 130(b), thesupports (for a bellows of different design: similar to that of FIG.129(a), are external. In FIG. 130(a), the supports comprise a centercolumn of large diameter (shown smaller for clarity) which is attachedto the bellows inner surface at intervals by a ring-shaped membrane thatis perforated to reduce contact area with the bellows. The membrane maybe horizontal as shown, if its width is very small, or may be angled atan angle greater than theta (i.e., of conical shape). Removal of thesupports can be achieved by collapsing the bellows so as to gain accessto each membrane, starting at the bottom, and cutting it away from theinternal bellows surface where it is attached between the perforations.The center column can also be cut toward its top and therefore shortenedso it does not interfere with the bellows reducing its length.

The bellows of FIG. 130(b) has supports in the form of external strutswhich link the bellows to a cylinder outside the bellows. The struts maybe horizontal if short, or if longer (as shown), may be built at anangle larger than theta. Removal of the supports may be accomplished,for example, by cutting open the cylinder and then cutting off all thestruts.

FIGS. 131(a) and 131(b) are 3-D sectional views of a bending actuatorwhich is not axially symmetric and in some embodiments can be builtwithout supports with its long axis along Z (the layer stackingdirection) and a sufficiently large angle beta (e.g., >45°). Wheninflated with a fluid, the thin wall on one side stretches, while thethick wall diametrically opposite it resists elongation, thus bending inthe direction shown. Anti-expansion rings similar to those of FIGS.129(a) and 129(b) may be provided—seen best in FIG. 131(a)—at least inthe area of the thin wall (or circumferentially as shown) to avoid“ballooning” of the thin wall. As can be seen from FIG. 131(b), the wallmay in some embodiments taper continuously from one side to the other,for example if the inside surface is circular but eccentric with respectto the outside diameter.

FIG. 132 is a cross-sectional view of an actuator similar to that ofFIGS. 131(a) and 131(b), but in which wire has been incorporated intothe elastomer to provide radial strength and avoid ballooning, in lieuof using anti-expansion rings. The wire may be continuous and, alongwith the deposited elastomer, form a helix (for example, and theeffective nozzle width may be changed while printing the structure(using the approach shown in FIGS. 46(a), 46(b), and 46(c) or 120(a),120(b), and 120(c)) so as to vary the wall thickness, for example.Alternatively, multiple wires, each forming a loop within a singlelayer, can be used, as shown in FIG. 132. The free ends of the wires canbe joined together (e.g., by solder or welding) to provide improvedmechanical strength, or the gap between the ends can be staggered (i.e.,unaligned) from layer to layer, or (as shown), the ends can be deformedinto anchoring structures such as the “J” shape shown in the figure, orother shapes such as “L” shapes, serpentines, and even complete ornearly-complete circles or other substantially closed paths, whichbetter anchor them in the polymer. In some embodiment variations,textured wire (e.g., embossed by the cutter/feeder rollers) can be usedto improve the anchoring of the wire within the elastomer, as canmelting the end of the wire to form a ball (e.g., using electronicflame-off), creating bulges on the fiber (at the ends and/or along itslength) using adhered solder or adhesive, twisting the wire (ifnon-circular in cross-section), etc. In lieu of or in addition to theanti-expansion rings in bellows designs such as that in FIGS. 129(a) and129(b), a wire loop such as that in FIG. 132 may be used.

Two or more of the structures of FIGS. 129(b) or 131(a) and 131(b),arranged in a group (e.g., a circle) with the stiffeners toward thecenter can behave as a fluidically-actuated hand, with each “finger”bending inward to grasp an object.

FIGS. 133(a), 133(b), and 133(c) show transparent 3-D views of acylindrical fluidic actuator that can be fabricated with FEAM fromelastomer and fiber. The actuator shortens axially when inflated withfluid, somewhat like a McKibben pneumatic muscle known to the art, andusually fabricated using a rubber tube and netting. When inflatedthrough the inlet at the proximal end, the cylinder wall bulges out;because of the encapsulated fibers, the distal end of the device ispulled axially toward the proximal end. The device is preferablyfabricated with the cylinder axis horizontal, as noted by the directionof the Z (layer stacking) axis in FIG. 133(a). In this orientation,fibers having good tensile strength may be encapsulated in a patternsimilar to that shown, with at least one U-shaped fiber (only one shown)encapsulated using FEAM on each side of the center axis on any givenlayer or set of adjacent layers, as shown in the cross-sectional view ofFIG. 133(b).

As discussed in the context of FIG. 132, the ends of each U-shaped fibercan be shaped into anchors as shown in FIG. 133(c), to better anchorthem in the elastomer. In some embodiment variations, rather thanintegrate two or more separate fibers on opposite sides of the axis asshown in FIG. 133(b), a single long fiber having the shape of anearly-closed loop, or a joined loop, can be used on a given layer. Theends of the loop can incorporate anchors in some embodiment variations.In some embodiment variations, the gaps for each wire loop are staggeredfrom layer to layer. Alternatively, the device can be built in a helicalfashion with continuous fiber forming a rectangular helix; if thegeometry requires thicker walls at the proximal and distal ends than thecylinder walls, a variable-width extrusion nozzle can be used asdescribed above.

In some embodiment variations, fibers within layers closer to thecylinder axis the cylinder can be longer radially (i.e., can have adeeper U-shape) than those closer to the top and bottom of the cylinder,and so have increased surface area for anchoring to the elastomer. Insome embodiment variations, in addition to anchoring methods describedabove, texturing the fibers, heating them during encapsulation,providing a coating on the fibers which promotes bonding to theelastomer, and other methods can be used to ensure that fibers will notbe easily pulled loose during inflation.

In some embodiment variations, rather than a circular cross-section, theactuator can have other shapes such square, hexagonal, and octagonal. Insome embodiment variations, the sides of the cylinder may be pleated(e.g., circumferentially or axially) to allow for greater expansion ofthe wall. In some embodiment variations, asymmetry can be introduced(e.g., by thickening a portion of the cylinder wall, varying the shape,diameter, or type of fiber) so that upon inflation, the actuator bendsinstead of shortening, or in addition to shortening.

FIG. 134(a) is a 3-D transparent view of a drive belt (a V-belt asshown, but other cross sections are equally possible) made using FEAMfrom an elastomer and reinforcing fibers. In the example shown, thereare three reinforcing wires, each encapsulated on a different layer. Asshown in the cross-sectional 3-D transparent view of FIG. 134(b), thefibers in some embodiment variations have the form of nearly-closedloops which may be provided with “J”-shaped anchors at each end. Thelocation of the gap is shown staggered from loop to loop. For example,with the three fiber loops shown in the figures, the gaps may bearranged to be 120° apart. At most locations, the belt is strengthenedby a three continuous fibers, while at the gaps, it is strengthened byjust two. By using even more fibers with staggered gaps, the strengthuniformly along the circumference of the belt can be improved evenfurther. A drive belt may also in some embodiment variations be made ina helical fashion using continuous wire. If the cross-sectional profileis not rectangular, then the variation in width required on each layercan be accommodated using a variable-width nozzle.

FIGS. 135(a) and 135(b) depict cross-sectional elevation views ofelectromagnetic devices in which the coils are monolithically fabricatedwith and integrated with soft magnetic elements such as a core andarmature. Normally, coils are insulated by a non-magnetic material suchas a lacquer, and coils can be made using FEAM in which a dielectricsuch as a thermoplastic like ABS forms the insulation. However, an SMPC(containing magnetic particles such as Potters SN08P40 or SI03P40 in adielectric matrix) can also be used as insulation, in which case it canalso serve to form magnetic elements which are highly integrated withthe coils, and which increase performance because of the highpermeability of the insulation compared to a typical coil. For example,an SMPC can be formulated using a powder such as ATOMET 1001HP. If thepowder concentration is substantially below the percolation threshold,the resulting SMPC has magnetic properties, but has negligibleelectrical conductivity. In the case of a polymer- or ceramic-coatediron, steel, nickel, or cobalt, powder, even higher concentration ofpowder can be used. Thus an electromagnet such as that in FIG. 135(a)can be fabricated in which the core and winding insulation are bothSMPC, and the entire device built monolithically using FEAM. Such anintegrated electromagnetic may be used as part of a relay, a vibratingdevice for haptic feedback, a bell, or of course, as an electromagnetthat picks up ferromagnetic objects. Similarly, the coil and armature ofthe solenoid actuator in FIG. 135(b) can be built monolithically fromSMPC using FEAM, with the plunger built either separately ormonolithically along with the other elements. Rotary as well as linearactuators can be built in this fashion. In the figures, the flux linesshown are merely representative of many such flux lines in an actualdevice.

FIGS. 136(a), 136(b) and 136(c) depict 3-D views of a variablereluctance motor with axial flux path that can be fabricatedmonolithically without assembly (or in separate pieces, and thenassembled), entirely with FEAM. Variable reluctance motors do not use amagnet in their construction, thus potentially facilitating fabrication;however, motors using permanent magnets are also possible, especially inview of recent developments in 3-D printing of magnetic structures usingPMPCs (NdFeB powders mixed with binders and extruded in an FDM-typemachine [Huber et al., 2016]). Moreover, solid magnets (e.g., sinteredNdFeB magnets in the form of thin disks, stacked until the desiredheight is reached) can be inserted into fabricated structures. In thepartial sectional view of FIG. 136(a), the three main components of themotor are shown assembled. These components are a stator/housing, adouble-disk rotor with integrated salient poles, and a set of coils (sixin the example shown). As is the norm with reluctance motors, the numberof coils exceeds the number of poles on the rotor. The stator/housingand rotor are composed at least in part of SMPC. Most designs forvariable reluctance motors require coils whose axes are radial; however,it is more difficult to fabricate high-quality coils using FEAM withsuch an orientation. With all coil axes parallel and axial, fabricationbecomes much more straightforward, and coils (e.g., of the design shownin FIG. 123) can readily be made one layer at a time, along withbuilding all the other required parts. Moreover, it can be easier toobtain small air gaps between the rotor and stator if the gap isparallel to the layer plane.

FIG. 136(b) shows the motor in section view with the rotor hidden, andFIG. 136(c) shows the rotor by itself. The rotor's upper and lowerdisks, salient (protruding) poles, and central shaft, complete themagnetic circuit of the magnetic fields generated by the coil and core.To reduce moment of inertia and potentially to better control the flux,the rotor disks may be perforated with cutouts as shown. The top andbottom of the rotor is provided with conical pivots which fit into(e.g., conical) depressions in the stator/housing, allowing for rotorrotation with reasonably low friction. In some embodiment variations,bearings or bushings (e.g., standard ball bearings) may be insertedduring or after fabrication in lieu of pivots. In other embodimentvariations, bearings or bushings may be fabricated monolithically (e.g.,sleeve bearings made from PTFE-thermoplastic or bronze-thermoplasticcomposites, PEEK, polyimide, nylon, acetal, ultra-high molecular weightpolyethylene, or filled versions of these materials; ball bearings;roller bearings, etc.). The stator provides support for the coils,cores, and rotor; it may be provided with a viewing hole as shown toallow observation of the spinning rotor, etc. Support material,preferably soluble such as PVA, is used as required during monolithicfabrication of the motor, such as between the stator housing and rotorlower disk, or between the lower disk salient poles and coils, forexample.

FIG. 137(a) shows a cross-sectional elevation view of the motor of FIGS.136(a), 136(b), and 136(c). The magnetic flux generated by the coil andcore passes through the small (horizontal, or axial) upper gap betweencore and salient pole, when the rotor is rotated to align the polesufficiently with the core, and then sequentially through the uppersalient pole, the upper disk, the rotor shaft, the lower disk, the lowersalient pole, the lower gap, and back into the core. In some embodimentvariations, only the upper or lower disk is provided. The motor may beoperated as a stepper, or operated continuously as a switched reluctancemotor, in which case a shaft position sensor may be used (e.g., using amonolithically-fabricated inductive sensor, or else an optical or othersensor), or a digital signal processor such as the TMS320F243 of TexasInstruments (Dallas, Tex.) may be used in the drive electronics.

Alternative designs for an axial flux reluctance motor are shown inFIGS. 137(b) and 137(c); these designs use a single rotor disk. In FIG.137(b), the rotor disk is provided with upper and lower salient poles,and the core of the coil is extended above and below it to form aC-shaped pole piece. Into the large gap of this structure fits the rotorand poles, forming a complete loop of magnetic material, except forsmall upper and lower horizontal (axial) gaps. In some embodimentvariations only one salient pole (upper or lower) may be used at eachposition on the roller: the gap is therefore smaller to accommodate thethinner rotor. A rotor such as that of FIG. 137(b) can have a lowermoment of inertia than that of FIGS. 136(a), 136(b), and 136(c);however, in some applications (e.g., a gyroscope) this may be adisadvantage. The design in FIG. 137(c) involves an extension of thecore into a U-shaped pole piece. With this approach, there is onesalient pole per position on the roller, and it projects radially towardthe pole piece, with upper and lower gaps that are vertical (radial),not horizontal.

Since the shaft in the design shown in FIGS. 136(a), 136(b), and 136(c)does not penetrate through the stator/housing, extraction of power bythe motor can be achieved by fabricating a spur or bevel gear, pulley,or sprocket between the rotor and one or both pivots, and including anopening in the side of the stator/housing to provide access to this newrotating element. For example, an external spur gear can enter theopening and mesh with the internal gear, or a shaft at right angles tothe motor shaft can be equipped with a bevel gear that passes throughthe opening to engage a bevel gear concentric with the motor shaft. Or,a chain or drive belt can penetrate through the stator/housing and wraparound an internal sprocket or pulley. In some embodiment variations,one of the pivots can be in the form of a truncated cone and not oneending in a sharp point as shown. The shaft (or a smaller diameterextension of it) can then pass through the cone(s) so it is accessibleoutside the motor stator/housing; since the contact area of such a coneagainst the depression in the stator/housing is much larger than in thepivots of FIGS. 136(a), 136(b), and 136(c), friction in this conicalbearing will be greater. However, this can be compensated if desiredthrough the use of gears that increase torque, since in someembodiments, gearing (e.g., planetary reduction gears) can beincorporated into the motor stator/housing, and built monolithicallywith the motor.

Other motor designs can be achieved with FEAM, both involving permanentmagnets (e.g., a permanent magnet stepper motor, a brushless DC motor, abrushed DC motor), and without magnets (e.g., an induction motor).

FIGS. 138(a), 138(b), 138(c), 138(d), 138(a′), 138(b′), and 138(c′)depict methods and apparatus for mechanically cutting wire with a bladewhich in some embodiments may be used in the FEAM process, asalternatives to that shown in FIGS. 33(a), 33(b), 33(c), 33(d), and33(e), which uses a separate anvil for cutting. In FIG. 138(a), twocapillaries—one a center capillary, and one downstream—are locatedcoaxially and spaced close together, separated only by a small gap. Wirepasses through both capillaries en route to the nozzle. Within the gap ablade (FIG. 138(a)) can be advanced from one side of the capillaries tothe other side, cutting the wire into two segments as shown in FIG.138(b), after which the blade can be withdrawn (FIG. 138(c)). If cutcleanly (with minimal burrs), the upstream segment of wire can beadvanced to enter the downstream capillary in preparation for the nextcut, while pushing further downstream the downstream wire segment. Tominimize burrs, the blade is preferably very sharp (e.g., the Featherblade made by Feather Safety Razor Co. (Osaka, Japan) and the gapbetween the capillaries is very small, so that the wire is wellsupported except where the blade must pass, and cannot bend in theprocess of being cut. An alternative design is shown in FIG. 138(d), inwhich a single capillary has been notched (e.g., by laser machining) butnot cut through, leaving a portion of the capillary to serve as ananvil. FIGS. 138(a′), 138(b′), and 138(c′) show a cutting sequencesimilar to FIGS. 138(a), 138(b), and 138(c), but using such a notchedcapillary. In this case, the blade must stop so that its edge does notpenetrate any further than the anvil surface (or perhaps a small amountbeyond it, if it is allowed to cut into the capillary). To the extentthat cutting of the wire does leave a slight burr, feeding of theupstream segment into the downstream capillary may be improved byvibrating the wire and/or one or both capillaries, twisting the wire,lubricating the wire (preferably with a liquid that evaporates quicklyor if it remains, does not contaminate the wire surface and impairelectrical contact or adhesion to matrix material.

FIGS. 139(a), 139(b), 139(c), 139(d), 139(e), 139(f), 139(g), and 139(h)are 3-D views of an apparatus for actively feeding and cutting wire (orother fiber, such as carbon fiber (individual strands or prepreg),Kevlar, or glass fiber) in some embodiments in accordance with theapproaches and apparatus of FIGS. 138(a), 138(b), 138(c), 138(d),138(a′), 138(b′), and 138(c′). In some embodiments, wire is not fedactively, but rather, fed passively, pulled through the capillary bybeing anchored in some fashion on the fabricated object (e.g., capturedby solidified extrudate). In some embodiments, a slip clutch or activedrive mechanism (e.g., using closed-loop tension sensing) can be used toregulate tension on the wire when wire is feeding passively (tensionsensing may also be useful when wire is fed actively).

However, to allow starting a wire segment that has been cut, activefeeding is desirable. In FIGS. 139(a), 139(b), and 139(c), general viewsof a feeder/cutter for reasonably soft, small diameter wire (e.g.,copper or nickel wire 0.008″ diameter or less) are provided. Thefeeder/cutter comprises a wire feeding section on the left (similar insome respects to the apparatus of FIGS. 32(a) and 32(b)), a wire cuttingsection in the center, and a wire delivery section on the right. A baseplate, which in some embodiment variations may comprise severalassembled pieces, provides a common support for all sections.

The feeding section comprises a pair of rollers—one driven by a steppermotor and one a spring-loaded idler, and support for the upstream andcenter capillaries. Within the small gap between upstream and centercapillaries, the rollers impinge on opposite sides of the wire passingthrough the upstream capillary, pulling wire from a feed spool (thoughin some embodiment variations the wire may be actively fed from thespool), and advancing it into the center capillary. The cutting sectioncomprises a mounted blade capable of controlled vertical motion, asolenoid to provide that motion, and support for the center anddownstream capillaries. Finally, the delivery section comprises thedownstream capillary, supported at the downstream end of the downstreamcapillary by a tapered portion of the base plate, allowing thedownstream capillary to be placed adjacent to or under the printheadnozzle. FIG. 139(d) is a closeup 3-D view of the blade passing betweencenter and downstream capillaries, as described above in the context ofFIGS. 138(a), 138(b), and 138(c). FIG. 139(e) is a sectional 3-D view ofthe feeder/cutter along the axis of the capillaries, while FIG. 139(f)is a closeup of FIG. 139(f) showing the blade passing between thecapillaries. FIG. 139(g) is a 3-D closeup view sectioned perpendicularto the capillary axes showing the drive rollers and the force adjustmentmechanism. Finally, FIG. 139(h) is a closeup 3-D view of the undersideof the feeder/cutter showing the rollers and nearby capillaries.

With respect to the feeding section and referring to FIG. 139(g), wire(not shown) is fed between two rollers toward their bottom surfaces. Insome embodiment variations, a single roller and a fixed surface (e.g.,in lieu of the idler roller) having low friction (e.g., a block of PTFE)can be used, with the wire pinched between the roller and this surface.In some embodiment variations, more than two rollers may be used, and insome embodiment variations, more than one roller may be driven. Thesides of the rollers are preferably knurled (not shown), e.g., using afine pitch straight knurl, or otherwise textured to obtain bettertraction on the wire. Such a texture is imposed on wire by plasticdeformation particularly if it is soft, but unless it is so deep as tolead to wire buckling when the wire is pushed along by the rollers, itis of no consequence, and in fact, can increase the bonding between wireand matrix. The stepper motor drives the driven roller through a ballbearing which controls the roller position. In some embodiments, a servomotor or other rotary actuator may be used in lieu of a stepper motor.The ball bearing idler roller is fastened to a sliding roller mountwhich is pushed on by a spring placed between the mount and a slidingblock. Spring force, and thus, the force pushing the idler rolleragainst the wire, is controlled by an adjustment screw which turns in afixed thread and pushes on the sliding block. The mount includes a tabthat can be manually pulled to retract the idler roller from the wire,allowing the wire to move freely; in some embodiment variations, anactuator may be provided to move the mount automatically, e.g., to allowwire anchored in the fabricated object to be passively fed through thecapillaries under tension.

With respect to the cutting section and referring primarily to FIG.139(e), activation of the solenoid causes the plunger to descend andpush against the top of a flexure (e.g., spring steel) which is rigidlyattached to the solenoid support on one side, and allowed to slide in agap between portions of the support on the other side. In someembodiments, a pneumatic cylinder or other actuator can be used in lieuof a solenoid. Attached to the flexure is a blade mount, which secures adouble-edge razor blade between two solid pieces. The blade ispositioned slightly off center with respect to the capillary axes, suchthat by removing and rotating the blade around a vertical axis, anunused sharp section of the blade may be used. By rotating the bladeabout a horizontal axis, access to its upper edge may be obtained. Thusfour regions of each blade can be used. In some embodiment variations,the blade can be slid parallel to its edges either manually or via anactuator, allowing even more use of the blade edge. In some embodimentvariations, the blade is circular in shape and can be rotated graduallyor intermittently to provide a sharp region for cutting once anotherregion has dulled from use. In the case of multiple fibers encapsulatedin the same extrudate, multiple feeders may be used in some embodiments,or a common feeder may be used, and a common cutter or multiple cuttersmay be used.

In use, the feeder/cutter may be mounted in some embodiments so theextended tip of the downstream capillary is located approximatelyadjacent to the tip of the nozzle as shown in FIG. 140. In the figure,the capillary tip is shown as curved, which in some embodiments it maybe, while in other embodiments the tip may be straight, and thefeeder/cutter may be mounted so the capillary is tilted down slightly.In FIG. 140, the nozzle motion relative to the fabricated object, whiledelivering extrudate to encapsulate the wire is not shown, but is towardthe right. In general, the downstream capillary inside diameter shouldbe large enough to feed wire easily, including cut pieces of wire whichmay have small burrs at the cut ends. The capillary outside diametershould be as small as possible, allowing the capillary to be placedclose to the underlying layer if required, and minimize the risk ofinterference between the capillary and previous deposits, as for examplewhen printing a spiral coil from the outside to the inside. If the wireis unheated, in some embodiments it is desirable to position thecapillary so that the wire is as high as possible, possibly touching theunderside of the nozzle, since the flow of matrix material (e.g., moltenpolymer) can tend to push the wire down towards the bottom of theextrudate, e.g., due to viscous drag. The size and the shape of the wire(e.g., square vs. rectangular vs. circular), the wire material (e.g.,thermal conductivity and specific heat), the size of the nozzle orifice,the properties of the matrix material, the material flow rate, thetemperature, and other factors may influence any such tendency. Inembodiments in which the wire is heated (e.g., by passing through one ormore capillaries heated by a thin-film heater, Joule heating, hot air,etc.) however, this effect may be reduced (e.g., since the viscosity ofthe flowing material is reduced by the higher temperature in thevicinity of the wire), thus the capillary location and angle may beadjusted to position the wire lower within the extrudate. In someembodiments, especially if the layer thickness is relatively large andthe capillary outside diameter small, the capillary tip itself may bepositioned under the nozzle tip. In some embodiments, grooves, bosses,or other features in the nozzle may serve to guide the wire into theextrudate at the optimal position and angle, and the capillary may befurther away from the nozzle tip.

The feeder/cutter may be mounted in some embodiments so that it can bemoved and adjusted in position either manually or using actuators alongthe X, Y, and Z axes (these X and Y axes are defined in the coordinatesystem of the FEAM system, and are not to be confused with the X and Yaxes of the platform if the platform is rotated; X is assumed to beroughly parallel to the capillary in this case). Movement along the Zaxis (and in some embodiments, sequential or simultaneous movement ofthe X axis as well) allows the capillary to be retracted, as alreadydiscussed in conjunction with FIGS. 30(a), 30(b), and 30(c). Adjustmentsalong the Z axis can assist with obtaining vertical concentricity of thewire and extrudate. Adjustments along the Y axis (perpendicular to theextrudate) can assist with obtaining horizontal concentricity, andadjustments along the X axis may be desirable for precise positioning ofthe capillary and control over the wire, especially for small radiusturns. In some embodiments, motion along the Y or the Z axis can be usedto create encapsulated wire that has a serpentine shape, allowingstretchability if the matrix is elastomeric, for example, andsimultaneous motion in Y and Z enables the production of helical wireshapes such as in FIG. 72. In some embodiments, small Z and/or Y axismotions/vibrations (e.g., 10-100 μm), e.g., at high speed may assistwith the extrudate flowing around the wire, which is desirable for theintegrity of the object (e.g., interlayer and intra-layer bonding withother extrudates) and to reduce any tendency to push the wire downtowards the bottom of the extrudate.

In use, the adjustment screw is tightened enough to provide goodtraction of the rollers on the wire, and wire is fed at a velocity thatin some embodiments matches the nozzle velocity with respect to thefabricated object. In some embodiments, the wire may be fed at a fasterspeed (e.g., to induce buckling into a serpentine shape that can bestretched) or at a slower speed (e.g., to induce tension in the wirewhich will be relieved when the surrounding matrix shrinks. When wireneeds to be cut, the solenoid is activated briefly, lowering the bladeand forcing it through the full diameter of the wire. When the solenoidis deactivated, the flexure then raises the blade so its edge is abovethe wire. Once a segment of wire is cut, activation of the stepper motorcauses wire upstream of the blade to advance, pushing the cut piecethrough the downstream capillary. In some embodiments, before cuttingoccurs, feeding of the wire by the rollers is ceased, while in otherembodiments, it can continue, as long as the cutting is very rapid orthe wire passes through a “buffer” zone (e.g., a section of thefeeder/cutter where it can controllably buckle) so it doesn't kink.

If a long wire segment is anchored in the fabricated object and beinglaid and encapsulated, then in general the feed rollers will be feedingwire as long as the nozzle is moving. However, once the segment is closeto being completely laid and played out by the downstream capillary, thefeed rollers in some embodiments are not active continuously, but may beturned on and off so as to allow cutting of wire segments “on the fly”without having to pause the printing process. FIGS. 141(a), 141(b),141(c), 141(d), 141(e), and 141(f) depict in cross-sectional elevationviews a sequence that demonstrates this, in which segments are cut thatare shorter than the downstream capillary. In FIG. 141(a), wire segment1 is anchored in the fabricated object and the feeder/cutter and nozzleare moving relative to the object to the left, away from the point ofanchor. Segment 1 has already been cut, and additional wire upstream ofit can now be cut without needing to stop the nozzle and feeder/cuttermotion. As shown in FIG. 141(a), segment 2 of the wire can thus be cutwhile the feeder/cutter is moving. In FIG. 141(b), the blade isretracted and segment 2 remains in the downstream capillary whilesegment 1 continues to be pulled out of it due to the feeder/cuttermotion away from the anchor point. In FIG. 141(c), wire feeding by therollers continues, feeding wire beneath the blade in preparation forcutting segment 3, while simultaneously pushing segment 2 further downthe capillary. In FIG. 141(d), the blade is lowered, cutting segment 3loose. In FIG. 141(e), the blade has retracted again, and by now, thegap between segments 2 and 3 has grown. Then, in FIG. 141(e), wire isfed again in preparation for the next cut, and also serving to pushsegment 2 out of the capillary (partially) and push segment 3 furtherdownstream. In general, wire segments which are short enough to remainin the capillary may be pre-cut while other operations are occurring. Ifthere is excessive motion or vibration that might allow cut segments tospontaneously move down the downstream capillary and even fall out, athin flexible wire or other element may be incorporated into thecapillary to provide a small, controlled frictional resistance tomotion, for example.

FIGS. 142(a), 142(b), 142(c), 142(d), 142(e), 142(f), and 142(g) depicta cross sectional views (elevation or plan) of a method for breakingwire in lieu of cutting it, and translating at least one capillary toclose the gap between the center and downstream capillaries. Bystretching wire to break it, the method minimizes the occurrence ofburrs on the ends of the segments, thus facilitating their feeding intoand passage through the capillaries. In FIG. 142(a), wire is in thedesired axial position, ready for segmentation. The capillaries arepreferably at least in the regions shown made from a deformable, highlyelastic material such as superelastic nickel-titanium. In FIG. 142(b)the capillaries have been squeezed (e.g., by pins or clamps not shown)such that they impinge tightly on the wire and clamping it securelywithin both capillaries. Then in FIG. 142(c), the center capillary (orin some embodiment variations, the downstream capillary, or both) hasmoved away from the downstream capillary, causing the wire to neck andthen, in FIG. 142(d), break in the necked region. Then, as in FIG.142(e), the capillaries can expand, releasing their grip on the wire. InFIG. 142(f), the center capillary has translated in some embodimentvariations so it is again adjacent to the downstream capillary, thusproviding a continuous conduit for the wire and facilitate the upstreamwire segment's entry into the downstream capillary. Finally, in FIG.142(g), the upstream wire has advanced (e.g., by feeder/cutter feedrollers) and has begun to push the downstream segment out of thecapillary. In some embodiment variations, prior to stretching the wire,the wire may be partially cut, or nicked, to facilitate breaking ortearing it.

FIGS. 143(a), 143(b), 143(c), and 143(d) depict 3-D views of a nozzleand hot end block which may be used for laying wire such as flatmagnetic (e.g., iron) wire side by side, as described in FIGS. 107(a),107(b), 107(c), 107(d), and 107(e). In some embodiments, such a nozzleand block may also be used for precisely controlling the placement ofisolated wire or other fiber as well. The hot end block is heated by acartridge heater (not shown) and thermoplastic material is fed into itthrough a feed hole. As shown in FIG. 143(a), the nozzle is equippedwith a flange and pressed against the block by a ring (not shown) thatsurrounds the flange and is retained by screws entering several holes inthe block, or directly by the screw heads or washers. Between the blockand nozzle is an O-ring in some embodiment variations.

The flat tip of the nozzle includes several features, comprising anorifice and several features that are not axially symmetric, as shown inFIG. 143(b). Before tightening the mounting screws, the nozzle can berotated relative to the block to align these features parallel to thedirection in which wire is to be laid. The two remaining featuresinclude a guide whose function is described in conjunction with FIGS.107(a), 107(b), 107(c), 107(d), and 107(e), and a spacer whichestablishes the desired gap between the nozzle tip and the top of thewire, and controls the thickness of extruded material that coats thewire when laid. This further affects the spacing of wire along the Zaxis. FIGS. 143(c) and 143(d) depict flat wire placed under the nozzletip such that it contacts the spacer at its top, and the guide at itsside.

FIG. 144(a) is a front view, and FIGS. 144(b), 144(c), 144(d), 144(e),144(f), and 144(g) are 3-D views, of a feeder/cutter for heavy gaugewire or other fiber difficult to cut using a sharp razor blade, such assteel wire which can be used in magnetic structures as an alternative oradjunct to SMPC. Such wire can be square in cross-section as in FIG.107, or rectangular. In some embodiments the wire is rectangular andoriented with the larger dimension parallel to the layers of thefabricated object. This allows thin layers (assuming the wire is notaller than the layer) while permitting larger areas to be formed usingfewer wires. Moreover, the wire may be easier to lay in straight,parallel lines. This type of wire, oriented as described, will beassumed in the following description of FIGS. 144(a), 144(b), 144(c),144(d), 144(e), 144(f), and 144(g).

Like the feeder/cutter of FIGS. 139(a), 139(b), 139(c), 139(d), 139(e),139(f), 139(g), and 139(h), wire is pinched between two rollers—onedriven by a motor and one, a spring-loaded idler (spring not shown). Ifthe wire were square in cross-section, then it could be driven eitherwith vertical or horizontal rollers. Assuming it is rectangular,however, in some embodiment variations it is driven by rollers above andbelow it rotating on horizontal axes as in FIG. 144(f), such that therollers contact the wider surface of the wire. In other embodimentvariations, the wire is driven by rollers rotating on vertical axesalong the wire's narrower dimension. In such a case, grooves may beprovided in the rollers into which the wire enters partway so as tominimize the risk of the wire twisting or distorting, and to increasetraction on the wire. The rollers are preferably knurled as alreadydescribed regarding FIGS. 139(a), 139(b), 139(c), 139(d), 139(e),139(f), 139(g), and 139(h). In the design shown in the figures, thedriven roller is turned by a drive shaft supported by bearings, and atiming pulley fixed to the drive shaft is turned by a timing belt (notshown) which is moved by a motor above the base plate turning anothertiming pulley (not shown).

The feeder/cutter may in some embodiments (as shown) incorporate the hotend block and nozzle of FIGS. 143(a), 143(b), 143(c), and 143(d) and afilament (or other) extruder, or these may be separate components. Ineither case, as shown in FIG. 144(a), the design of the feeder/cutterincorporates a base plate which is angled much like that in thefeeder/cutter of FIGS. 139(a), 139(b), 139(c), 139(d), 139(e), 139(f),139(g), and 139(h); however, the angle in this case may be larger sothat the bearing which supports the drive roller shaft is higher thanthe tip of the nozzle, and so cannot interfere with the fabricatedobject's top layer while building. With vertical axis rollers, the anglecan be smaller in some embodiment variations.

To cut wire, the feeder/cutter may use a number of approaches.Preferably the wire is cut along its narrow dimension (i.e., verticallyif oriented as described above) to avoid the risk of twisting. However,sufficient vertical clearance may not be available to cut the wirevertically if an anvil or second cutting blade must be located under thewire. Thus in the approach shown in FIGS. 144(a), 144(b), 144(c),144(d), 144(e), 144(f), and 144(g), cutting is performed along the widedimension of the wire, and the wire is prevented from twisting by thecenter and downstream capillaries, which in some embodiment variationsare rectangular in cross section, and just slightly larger in insidedimensions than the wire. In the particular implementation shown,ordinary high quality wire cutters are used to cut the wire; in otherembodiment variations blades may be mounted to low-profile fixed,sliding, or compliant elements, thus eliminating the large, traditionalwire cutter and allowing for a more compact design. As shown in FIG.144(c), a pneumatic cylinder is provided that when actuated, pressesagainst one handle of the wire cutters using a push plate, while theother handle is prevented from moving by a backstop. In some embodimentvariations, rather than have one blade fixed and one move, both aremoved inwards toward the center of the wire to cut it. FIG. 144(e) is acloseup of the fixed and moving wire cutter tips protruding through anaperture in the base plate, and surrounding the rectangular capillaries(wire not shown).

In operation, wire is pulled from a spool (not shown) through theupstream capillary, then pushed through the center and downstreamcapillaries, as with the feeder/cutter of FIGS. 139(a), 139(b), 139(c),139(d), 139(e), 139(f), 139(g), and 139(h). The capillaries are mountedto a capillary holder on the underside of the base plate, and the tip ofthe downstream capillary is located near the tip of the nozzle (FIG.144(g)). Once wire is cut, the downstream segment is pushed into thedownstream capillary (the upstream inlet of which may be flared) by theadvancing uncut wire in the center capillary, as in the feeder/cutter ofFIGS. 139(a), 139(b), 139(c), 139(d), 139(e), 139(f), 139(g), and139(h). In some embodiment variations, the capillaries are in the formof grooves machined into the base plate of the feeder/cutter, andcovered with a thin shim (e.g., stainless steel) on the bottom surface.

In addition to the double-blade cutter shown in FIGS. 144(a), 144(b),144(c), 144(d), 144(e), 144(f), and 144(g), in some embodimentvariations other cutting methods may be used. These include the methodof FIGS. 142(a), 142(b), 142(c), 142(d), 142(e), 142(f), and 142(g), arotating element such as a blade, cutoff wheel, or dicing saw blade(e.g., diamond or other hard material), single-blade cutter with anvil,laser cutter, and plasma cutter. With some of these methods, cooling maybe advisable, such as using spray cooling with a quickly-evaporatingcoolant, or using a cold air blaster or other source of cold gas. Also,means of collecting dust such as a vacuum and/or a surface coated withadhesive may be used. In some embodiments, wire may be cut simply byproviding a shearing action (horizontally and/or vertically) between thecenter and downstream capillaries with no gap between these. Thecapillaries are preferably fabricated in the form of channels in rigidplates of hard material, with sharp edges.

As with the wire feeder/cutter of FIGS. 139(a), 139(b), 139(c), 139(d),139(e), 139(f), 139(g), and 139(h), the feeder/cutter of FIGS. 144(a),144(b), 144(c), 144(d), 144(e), 144(f), and 144(g) may be mounted insome embodiments so that it can be adjusted in position either manuallyor using actuators along the X, Y, and Z axes.

FIGS. 145(a), 145(b), 145(c), and 145(d) depict 3-D views of an extruderfor FDM and FEAM use, similar in some respects to that shownschematically in FIG. 49, though without the piston and actuator, orextra hopper to introduce powder. Such an extruder is able to feed andextrude a very wide range of materials, from hard materials such as ABSto very soft TPEs (e.g., 5 Shore A), typically materials softer thanabout 75 Shore A cannot be extruded by filament-based extruders. Theextruder comprises a motor (e.g., a stepper), a gearbox which reducesspeed and increases torque, a hopper for polymer pellets, a feed screwinside a close-fitting barrel, a coupler to couple the gearbox output tothe feed screw, a hot end block, one or more band heaters in someembodiment variations (not shown), a nozzle, a motor mount, a barrelmount, and a heat sink. The overall design of the extruder has materialprogress from hopper through barrel and hot end block, and extrude outthe nozzle. The axis of the extruder barrel is at an angle (e.g., 45°)to the horizontal while the angled hopper allows material to be loadedas if the barrel were horizontal, and the hot end block is shaped so theaxis of the nozzle is nonetheless vertical. The hopper is retained inthe position shown by the hexagonal outer shape of the barrel and acorresponding hexagonal recess in the lower end of the hopper; the endof the barrel toward the motor is circular. By sliding the hopper alongthe circular portion of the barrel toward the motor, it can be rotatedin order to dump the pellets inside, e.g., when changing materials. Insome embodiment variations, a vibrator or other agitator is affixed tothe hopper to assist in feeding materials (e.g., low-durometer TPEs)into the barrel.

Material is heated as it progresses down the barrel toward the hot endblock, which is heated by a cartridge heater or similar. One or moreband heaters may be located along the barrel between the heat sink andhot end block to pre-heat the material. The barrel mount and heat sink(onto which a cooling air stream may be directed) provide a means ofdissipating heat so that pellets upstream of these elements are notprematurely heated, which can cause them to agglomerate and not feedproperly.

As shown in the sectional 3-D view of FIGS. 145(c) and 145(d), withinthe barrel is a feed screw with flights that is rotated to feed materialinto the hot end. Since the feed screw diameter must be small (e.g., ⅜″)for use in FDM and FEAM, the flight depth is preferably large enough forpellets of standard size to fit into them. An auger bit intended fordrilling, but rotated backwards, is an example of a suitable feed screw.Material enters the feed screw through an aperture in the upper surfaceof the barrel, below the hopper.

In FDM and FEAM, it is often necessary to reverse the flow of extrudedmaterial before making a jump between one printed area and another toavoid oozing from the nozzle that can cause a “stringer” (thinextraneous material). This is known as suck-back or retraction. If thisis done, before extruding again, the extruder normally is primed suchthat it is full of fluid material and ready to extrude again. In theextruder of the current design, retraction and priming may beaccomplished in some embodiment variations by feed screw rotation alone(e.g., reversing the normal feed direction to retract), though a highspeed of rotation for retraction (and optionally, priming) may bedesirable. In some embodiment variations, the hot end block is equippedwith a piston and cylinder similar to that of FIG. 49, to rapidlyrelieve pressure or establish a partial vacuum in the hot end block andprevent oozing. In some embodiment variations, the feed screw itself maybe retracted axially by a suitable actuator to aid in retraction. Insome embodiment variations, in addition to the feed screw shown, asecond, smaller feed screw is provided with its axis parallel to thenozzle, and inserted into the hot end block and/or nozzle tosubstantially block the flow from the nozzle when the smaller feed screwis stationary. Upon rotation of the smaller feed screw, flow commences,and upon stopping the smaller feed screw or reversing it, flow isquickly stopped and if desired, retracted (in which case, the nozzle canalso be primed in preparation for the next extrusion). Indeed, thissmaller, low-inertia feed screw can serve as the primary regulator offlow from the nozzle, at whatever rate is required, and the larger feedscrew can serve primarily to replenish material in the hot end that isejected by action of the smaller feed screw.

The extruder of FIGS. 145(a), 145(b), 145(c), and 145(d) is more massivethan typical filament extruders, and thus as shown is more difficult tomove in X and Y relative to the platform on which the object is beingfabricated. In some embodiments, the platform is thus moved in X and Yand the extruder only moves in Z, or not at all. In other embodiments,modifications to the design in FIGS. 145(a), 145(b), 145(c), and 145(d)can be made to lighten it, thus better enabling it to move much like astandard filament extruder. In various embodiments such modificationsmay include:

A fixed, remote hopper, from which pellets travel through a tube (e.g.,driven by air flow, air pressure, vibration, or merely tube flexing inthe course of extruder motion) to the extruder.

A fixed, remote hopper under or adjacent to which the extruder, with ahopper of much smaller capacity, moves as needed to receive a new loadof pellets.

A fixed, remote motor (and in some embodiments, gearbox) with a flexibleshaft delivering torque to the moving feed screw and barrel.

A fixed, remote motor with a flexible shaft delivering torque to amoving gearbox, feed screw, and barrel.

A fixed, remote motor with a partial gearbox, and a flexible shaftdelivering torque to a moving partial gearbox, feed screw, and barrel(i.e., some of the reduction in speed and increase in torque isperformed at the fixed location, and some at the moving printhead). Afixed, remote hopper, motor, gearbox, feed screw, barrel, and bandheater, which delivers molten material to a moving hot end through awell-insulated and/or heated umbilical.

Use of an air motor with reduction gearing, or a spring motor/clockworkin lieu of an electric motor and gearbox.

Objects fabricated with FEAM from flexible materials such as TPE canhave support structures made from a material that is relatively rigid,such that the supports, rather than needing to be dissolved or cut away,can simply be peeled off of the object by flexing it. Moreover, rigidmaterials can be more vulnerable to crushing, sand or bead blasting,vibratory deburring, and similar approaches, than the flexible object,so these methods may also be used.

Objects fabricated with FDM and FEAM may not be isotropic in tensilestrength, for example, with the weaker axis being the Z axis, due tointerlayer adhesion not being generally as good as the bulk propertiesof the material. This can be particularly a problem for objects withsmall areas of overlap between layers, such as lattice-like designs. Inprincipal, material deposited on layer N fuses with that alreadydeposited and solidified on layer N−1; however, the fusion is incompleteand interdiffusion at the interface is imperfect. In some embodiments,therefore, the nozzle may be rotated at high speed or vibrated while itis extruding, such that its bottom surface exerts a viscous drag on thesoftened material on layer N−1, and helps to mix and inter-diffuse itwith material on layer N. The bottom of the nozzle may be textured orhave relatively large projections (a fraction of the thickness of layerN−1) to enhance this effect. In some embodiments, another method forenhancing inter-layer adhesion may be used, comprising arapidly-reciprocating, narrow heated needle which moves with the nozzle(e.g., it may be within the nozzle orifice) and penetrates layer N−1,“sewing” the two layers together by helping to intermix the material ineach of them. Such techniques of improving inter-layer adhesion, whilethey may generally useful when printing the part, may also intentionallynot be used in regions or under circumstances when it is desired thatinter-layer adhesion is relatively weak. For example, when making a partsupported by supports made from the same material as the part itself, itis desirable to reduce the adhesion at the interface between the partand supports such that support removal is easier, and less likely todamage the part or leave a small amount of the support behind.

In some embodiments, when co-depositing fiber and matrix material alonga path having small radii (e.g., the corners of a square), the forwardmotion of the nozzle and wire may be slowed or paused to allow moresolidification of the matrix to occur, and/or, additional matrixmaterial may be added to form a “staple” or localized blob that helps totrap the fiber and prevent it from herniating out of the extrudate.

In some embodiments, resistors with precise values may be produced frompartially-conductive materials such as ECPC, or a variety of commercial“conductive” filaments such as F-Electric made by Functionalize(Seattle, Wash.), as follows:

Deposit resistor material in a pattern (e.g., straight, serpentine)beginning with one end encapsulating a wire (which may be part of anexisting or planned circuit, or added for the purpose of monitoring theresistor value); electrically connect to this “probe” wire if notalready done.

Print the remainder of the resistor while measuring the resistancebetween the nozzle and the probe wire.

When the resistance reaches the desired value (compensating in someembodiments for expected changes, e.g., due to solidification or aging),encapsulate another wire serving as the other terminal of the resistorand stop printing the resistor.

This general approach can also be used for producing other componentswith well-controlled values, such as inductors and capacitors.

In some embodiments, wire that is anchored in matrix material orotherwise may be broken (instead of being cut) by nicking or scoring itwith a blade or other cutting element and pulling on it, preferably witha sudden jerky motion (e.g., raising the capillary, moving it sideways,or pulling the feeder/cutter away while the feed rollers are stopped, orreversing the rollers). In some embodiment variations, the wire may bebroken, if relatively brittle (e.g., glass or ceramic) by thermal ormechanical shock after being scored. Wire broken this way is alreadywithin the downstream capillary or has already exited from it, thus anyburrs produced do not affect the wire's ability to be transported.

Objects fabricated from elastomers in the FEAM process may beselectively stiffened in some embodiments by incorporating fibers withinthe structures in specific locations and with specific orientations.

In some embodiments, wire segments may be fed through a capillary from acutter such as that in FIGS. 139(a), 139(b), 139(c), 139(d), 139(e),139(f), 139(g), and 139(h) or 144(a), 144(b), 144(c), 144(d), 144(e),144(f), and 144(g) using vibration of the capillary (in some embodimentsfine springs, “hairs”, or “fingers” are incorporated inside thecapillary, pointing downstream), or using fluid flow (e.g., air injectedinto the capillary axially, or through louvers in the capillary wall:such louvers can be laser cut and then deformed into shape to direct airdownstream and not catch the edge of advancing wire), or using anexternal moving magnet to drag the segments (if ferromagnetic) along, orusing coils to propel them directly (if ferromagnetic) using theprinciple of the railgun.

In some embodiments, objects may be produced with fibers or otherinserts some of which are embedded using ultrasound or thermal means(e.g., FIGS. 70(a), 70(b), and 70(c)) and some of which are co-depositedand encapsulated using the FEAM process. For example, an object may beprinted with FEAM and then have additional fibers or other useful itemsembedded into it ultrasonically on accessible surfaces. In one suchapplication, wires can be embedded which form vertical vias betweenencapsulated wires laid parallel to the horizontal layers.

Ultrasonic transducers which may be used to embed fibers and otherelements such as in FIGS. 70(a), 70(b), and 70(c)) may not easilytolerate the environment of a heated chamber in which fabrication usingFDM or other AM process sometimes occurs. Thus in some embodiments thetransducer and associated elements such as the horn can be activelycooled and/or the transducer can be isolated within an enclosure (e.g.,one that moves across the surface of the part like a printhead) that istemperature controlled.

Since with FEAM the printhead may not be rotationally symmetric due tothe external, lateral placement of the capillary, and given that this iscompensated for by rotating at least portions of the printhead or thefabricated object, it is also possible to integrate other elements inthe printhead which are beneficial to the process. For example, trowelsand other protruding shapes attached to the printhead (e.g., the nozzle)can be used to control the width and shape of extrudates withconsiderable accuracy and precision, making possible objects withimproved tolerances and/or smaller features. These structures may besubstantially aligned with the nozzle orifice axis, or be locatedsomewhat upstream or downstream of the axis. In the case of an FDM orFEAM process carried out in a parallel, raster mode (as discussedbelow), such active shaping of the extrudate can minimize the stairstepsin the X/Y plane that would otherwise result.

In some embodiments in which flat wire is laid with the wider dimensionparallel to the layers, it is desirable to bend the wire within thelayer plane. Normally this is difficult without twisting it, but with anozzle or printhead attachment having a groove to accept a portion ofthe wire's width, such “edge bending” as it is known to the art, can beachieved, with surprisingly small radii if the material is ductile.

In some embodiments, the capillary and wire supply (e.g., spool), and insome cases even a feeder/cutter (collectively, the “WDS” (wire deliverysystem)), can be independent of the nozzle, and multiple instances ofthis apparatus may be provided in a single FEAM system. For example, theWDS can be translated on its own X/Y (and optionally theta) stages, ormove by piggybacking onto the moving printhead when needed. Byseparating the WDS from the nozzle and allowing independent movement ofeach, a structure such as the drive belt of FIGS. 134(a) and 134(b) (andfar larger and more complex structures) can be easily created withcontinuous wire, even without a variable-width nozzle. For example, theWDS and nozzle can follow the same trajectory while forming a singleloop of continuous wire, at which point the nozzle can move separatelyto fill in the remaining portions of the layer, while the WDS remains inplace with the wire uncut and intact. The converse is also possible, inwhich the wire laying is performed last on a layer. Toolpaths for bothWDS and nozzle which avoid collisions are of course necessary, and insome cases, the WDS may have to move small distances while playing outwire temporarily (and later retracting it) to avoid such collisions.With one or more WDSs, it becomes possible to build an object such asthe axial flux motor of FIGS. 136(a), 136(b), and 136(c) with multiplecoils, each made from continuous wire, with no junctions.

The 3-D views of FIGS. 146(a) and 146(b) depicts as separate pieces (forclarity) a structure to be printed having continuous wire and matrixmaterial in some volumes, but only matrix material in other volumes. Theprinting of such a structure is enabled by the ability to separatelymove the nozzle and WDS. In the example shown, the structure is a coilhaving one winding of wire on each layer as in FIG. 146(a), and“bridges” between wires which connect one winding to another; thesebridges may be at various angles, including vertical. The wire starts atthe bottom (and may have an elongated lead extending past the winding,not shown) and ends at the top (again, with a possible elongated lead).The wire will be encapsulated near the outside diameter of athick-walled cylinder of matrix material such as that of FIG. 146(b). Insome embodiments, coils with multiple windings on each layer (e.g., asin FIG. 123) may be similarly fabricated, as may be structures such asthe belt of FIGS. 134(a) and 134(b).

The plan views of FIGS. 146(c), 146(d), 146(e), 146(f), 146(g), 146(h),146(i), 146(j), 146(k), 146(l), 146(m), and 146(n) depict a sequence infabricating a layer of this structure. In FIG. 146(c), a nozzle isbeginning to move counterclockwise in a circular pattern starting at the6 o'clock position, so as to print wire and an extrudate of matrix on agiven layer (here assumed to be the first layer). Moving along with thenozzle is a capillary (and WDS) through which the wire is fed. As thenozzle moves, the capillary rotates so as to remain substantiallytangent to the nozzle motion as the nozzle moves (in some embodimentsthe capillary angle may be intentionally kept off-tangent to better keepthe wire centered in the extrudate, or bias it to one side of theother). In FIG. 146(d), the nozzle and capillary have moved to the 9o'clock position, and a quarter of the wire/matrix circle has beenprinted. In FIGS. 146(e) and 146(f), the nozzle and capillary have movedto the 12 o'clock and 3 o'clock positions, respectively, continuing toprint wire and matrix as they progress. In FIG. 146(g), the nozzle andcapillary have moved to a position slightly counterclockwise of 6o'clock, completing the first trace, comprising both matrix and wire.From this position, the bridge to the second layer, which comprises a Ztranslation of the WDS, can be initiated. However, prior to forming thebridge, it is necessary to print other portions of the layer, which willnot include wire.

To make room for the nozzle to move independent of the capillary, inFIG. 146(h) the nozzle and capillary have translated and rotated (ifboth are needed) to a new position, while playing out wire from the WDS(e.g., advancing the WDS' feed rollers, or releasing their grip on thewire). In FIG. 146(i), while the capillary remains stationary, thenozzle has begun to follow a toolpath which allows it to depositadditional matrix material on the layer, forming a portion of the secondtrace, which contains no wire. In FIG. 146(j), more of the second tracehas been printed, and in FIG. 146(k), trace 2 has been completed. Sincethe wall needs to be thicker, the nozzle then continues to print a thirdtrace, which is nearly completed in FIG. 146(l). After completing afourth trace, the nozzle then moves back in FIG. 146(m) to its normalposition adjacent to the capillary. In FIG. 146(n), the extra wire thathad been played out is retracted (e.g., by reversing the feed rollers)while or after repositioning the nozzle and capillary in locations whichallow the bridge to then be formed and the second layer to be printedusing a similar sequence similar to that shown in FIGS. 146(c), 146(d),146(e), 146(f), 146(g), 146(h), 146(i), 146(j), 146(k), 146(l), 146(m),and 146(n). This is repeated until all layers are formed; on the lastlayer the capillary may be moved while playing out wire so as to providea lead for the coil.

Had the structure needed wire closer to the inside diameter of the wall,the capillary and WDS may have instead moved inwards so as to be out ofthe way of the nozzle. In some situations, the nozzle toolpath mightordinarily cause the nozzle to move across wire (e.g., which has beenplayed out), potentially depositing material which then anchors the wireinadvertently to the previous layer. In some embodiments, to avoid this,the WDS (and/or the structure being fabricated) can be rotated around sothat the wire is always kept out of the way of the nozzle; therotational angles required to accomplish this may need to be updateddynamically as the layer is printed. While there is relative motionbetween WDS and fabricated structure, the wire joining them may need tobe adjusted in length dynamically so as to maintain the desired tension,avoiding the risk that a sagging wire may snag on the edge of a featureon layers already printed. Lifting the WDS when not in use can alsominimize the risk of snagging.

In some embodiments, an independently-moving WDS may have a dockingposition off to the side of the print area where it may move when notneeded. In some embodiments, wire may be deflected and shaped within theextrudate or outside the extrudate (e.g., as bare wire) using magneticforces. In some embodiment variations, these forces can help to maintainthe wire centered coaxially within the extrudate in the X/Y plane and/oralong the Z axis. In some embodiment variations, magnetic forces (usingalternative current to power an electromagnet) can cause the wire toassume a serpentine shape that facilitates the production of stretchablecircuitry. In the case of ferromagnetic wire, or non-ferromagnetic wiretemporarily made to carry a current, controlled currents may be appliedto one or more (e.g., an array) electromagnets incorporated into theprinthead in the vicinity of the nozzle, to apply forces to the wire. Insome embodiment variations, current may be passed through the wire bymaking one electrical contact through the spool and/or feeder/cutterrollers, and making the other electrical contact near the nozzle usingthe nozzle itself, or another element (e.g., a brush) to contact thewire.

In some embodiments, batteries (primary or secondary cells) can befabricated with that rely on dissimilar wire electrodes, such asaluminum, zinc, magnesium for one electrode, and copper, nickel, silver,platinum, or alloys of any of these for the other electrode, with anappropriate electrolyte (e.g., aqueous sodium hypochlorite, or bleach)[Qu et al., 2015]). For example, aluminum and copper wires can beencapsulated in the same extrudate, and separated by a porous fiberspacer which can be saturated with electrolyte (e.g., by wicking). Or,in some embodiments, suitable spacers can also serve as solidelectrolytes. In some embodiments, a spacer element can be incorporatedwhich later dissolves or is otherwise removed (e.g., by stretching andpulling it out, much like mandrels use in catheter manufacturing). Insome embodiments, batteries can be produced in which individualextrudates encapsulate different types of wire, and space is providedbetween extrudates as required for the electrolyte. Thus for example,one extrudate (e.g., a polymer such as low density polyethylene) mayencapsulate one or more aluminum wires, and a nearby extrudate mayencapsulate one or more copper wires. Between the two extrudates is aregion with no extrudates, or a region with extrudates that haveinterconnected pores. In this region electrolyte can be introduced. Theextrudates encapsulating wires may be porous to allow electrical contactbetween the wires and the electrolyte and/or may be interrupted (havingregions of bare wire exposed to the electrolyte). In some embodimentvariations, porosity in extrudates encapsulating wire, and in some casesother nearby extrudates, can provide an escape path for bubbles whichmay be generated during operation of the battery, and which can degradeits performance. In some embodiments, the electrolyte can be pumped orotherwise driven through channels, to allow bubbles to be removed. In adevice using FEAM-produced batteries, a pump can be provided for thisfunction. In a device that is elastomeric and is deformed frequentlyduring ordinary use, the deformation may itself provide pumping of theliquid through available channels, especially if one-way (check) valvesare provided, much like the venous system returns blood to the humanheart due to muscle contraction adjacent to veins. In some embodimentvariations, venting of the battery may be provided by the use of smallholes or hydrophobic membranes. In some embodiments, wires are straight,while in other embodiments, they are organized into complex and/orcompact shapes which provide large surface areas for the batterycomponents such as the electrodes (e.g., coils). In general, batteriesformed using the FEAM process can be distributed through a fabricateddevice and like many other components in FEAM, serve multiple functions,such as structural and electronic. Distributed power has a number ofadvantages, including greater energy storage capacity, redundancy,improved thermal management, higher voltages (if connected in series),and much greater design freedom, since the device need not accommodatethe limited and often rigid form factors of conventional batteries.

Loudspeakers, headphones, earphones, earbuds, dynamic microphones andgeophones, as well as voice coil actuators may be produced with the FEAMprocess, using PMPC as the magnet, or an inserted magnet. Acoustictransducers may also be produced without permanent magnet materials,using ferromagnetic materials and/or interacting coils only, forexample: If the motion produced is unidirectional, an AC signal to bereproduced can be combined with a DC bias to minimize distortion.Galvanometers which indicate the flow of current, or which rotatemirrors in scanning applications, can be fabricated using FEAM. only,

Displays of various kinds can be produced with FEAM. These includeelectrophoretic displays similar to those made by E Ink Corporation(Billerica, Mass.); field emission displays; electrochromic displays;thermochromic displays (e.g., using junctions at the intersections ofrow and column wires (rapidly-scanned as a matrix circuit) to heat alayer of thermochromic material, or extrudate mixed with thermochromicpigment(s); and liquid crystal displays.

Transformers that can be produced using FEAM include transformers withmultiple tapped or tapped windings and high voltage devices (e.g., Teslacoils). Arrays of coils can be used to accelerate and propelferromagnetic objects, e.g., as in a railgun.

In some embodiments, FEAM may be used to produce actuators andintegrated devices having wires serving as electrodes, and in whichactuation is produced by gases generated by electrolysis or otherchemical reactions activated by an electrical current.

In some embodiments, in lieu of a fiber originating in solid form, andintroduced into a matrix material which is solidified to encapsulate thefiber, as has been described in detail, the fiber may originate inliquid form, and become encapsulated nonetheless (e.g., by directing theliquid stream into the extrudate, to form a substantially coaxial liquidstructure. During or after the encapsulation, the fiber solidifiesspontaneously or be solidified actively (e.g., by UV curing), orpermanently remain liquid.

FIGS. 147(a), 147(b), 147(c), and 147(d) depict in elevationcross-sectional views a sequence for producing junctions using solderpaste, reflowed by focused energy (in some embodiments, a laser, as willbe assumed here, which can very rapidly produce solder joints with lowintermetallics and leaching, and with fine grain microstructures, withminimal damage to other materials and components). In some embodiments,a similar process may be used for forming junctions from other materials(e.g., ECPC which is dispensed at a relatively low temperature but thenis softened by heating to facilitate junction formation). While thefigures depict a process for producing inter-layer junctions, a similarprocess may be used for producing intra-layer junctions in someembodiments. In FIG. 147(a) the precursor for an inter-layer junction isdepicted, including a cavity in which two or more wires (e.g., copper,tin-coated copper) pass through. Wires need not pass entire through thecavity from one region of dielectric to another, but one or both wiresmay end within the cavity. Nevertheless, having the wire regions to bejoined anchored on both sides can facilitate junction formation,especially if contact with the wires is required to deposit or reflow(e.g., in the case of a soldering iron tip) the solder paste, and can behelpful when reflowing using a jet of hot gas.

In FIG. 147(b), a junction-forming cluster capable of moving adjacent toa layer, comprising a source of focused energy (here, a fiber deliveringa laser energy), a collimator if required to collimate the beam, and afocusing lens is provided, as well as a dispenser for solder paste andoptionally, a microscope. In some embodiments, not all of these are partof a cluster and may move individually, or the fabricated part may bemove relative to them. In FIG. 147(b), the microscope is positioned sothe desired, target location for the junction is substantially centeredon its optical axis or in another suitable, known location (e.g., thecenter of crosshairs). If the target location is variable (e.g., due toa non-repeatable position of the wires), this step allows for ameasurement (e.g., using computer vision software) which allows for thedispenser and beam axis to be adjusted to compensate for thevariability.

In FIG. 147(c), the cluster has moved so that the dispenser ispositioned over the target. The dispenser is assumed here to comprise asyringe filled with solder paste, a piston to displace the solder paste(e.g., when moved using pneumatic pressure), and a hollow needle, thoughin other embodiments other dispensing methods know to the art may beused. The dispenser may be lowered slightly toward the wires in someembodiments, after which the piston is lowered to displace a smallamount of solder paste through the needle onto the wires, while in otherembodiments no such motion is required. Once paste is dispensed onto thewires, the cluster moves such that the laser optical axis is alignedwith the solder paste as in FIG. 147(d), after which the laser is turnedon briefly to reflow the solder paste.

In some embodiments, rather than apply paste to both wires in aninter-layer junction at the same time as in FIG. 147(c), paste can beapplied to each wire individually, after the layer containing the wireis formed. The quantities of paste on each wire will tend to mergetogether before reflow. This approach may be particularly useful whenforming an inter-layer junction involve greater than two wires. In someembodiment variations, the paste on each layer can be independentlyreflowed. In some embodiments, the wires are copper wires which arecoated with a thin layer of tin to improve solderability.

In some embodiments a fume extractor (e.g., a nearby tube or an annularslot surrounding the lens connected to a vacuum source) may be used tocapture soldering fumes/particulate, which can help keep the opticsclean. A longer focal length lens may also be useful so that the fumesdo not directly impinge on the optics. A variety of solder pastes may beused, however, no clean lead-free formulations may be preferable.Suitable pastes include QuickAlloy 5LT138LF manufactured by CyberDoc LLC(East Setauket, N.Y.), ZeroLead ZLSP manufactured by Zephyrtronics(Pomona, Calif.), and PF606-P133H manufactured by Shenmao America Inc.(San Jose, Calif.), the last of which is specially formulated for lasersoldering. Junction resistances typically less than 10 milliohm areeasily produced. Moreover, if a laser having a wavelength in the nearinfrared (e.g., 800-1100 nm) is used, the radiation will be efficientlyabsorbed by the solder but heating of and damage to surrounding material(e.g., thermoplastic polymer) can be minimized. A 1064 nm 6 Wfiber-pigtailed laser (model LD-1064-UM-6 W from Innolume GmbH,Dortmund, Germany) is an example of a laser suitable for junctionformation, though lower power lasers and lasers with other frequenciesmay also be suitable.

The laser energy used to form a junction may be at a fixed power levelduring junction formation, or may vary in time (e.g., lower initially topre-heat the solder paste, activating the flux and pre-warming thewires, then higher to reflow the solder itself. Or, hot air, IR lampheating, general heating of the process chamber, or other means may beused for pre-heating in some embodiments. Multiple laser pulses withvarious duty cycles and frequencies may also be used in lieu ofcontinuous illumination. The laser may be raster or spiral scanned(e.g., by moving the stage on which the part is built) over areacontaining solder paste, wire, and/or pads during pre-heating, and laserfocal spot size may be altered for purposes of pre-heating (e.g., thestage may be raised or lowered to defocus the laser).

In some embodiments, junctions produced may have both inter-layer andintra-layer characteristics. For example, on layer N there may be onewire, while on layer N+1 there may be two wires in close proximity. Allthree wires may then be joined by conductive material, whether solder,ECPC, or other.

FIGS. 148(a), 148(b), 148(c), 148(d), and 148(e) depict elevationcross-sectional views of a process for producing soldered junctionswherein solid solder is dispensed and then melted by a jet of heated gas(here assumed to be air). In some embodiments, the flow of hot air maybe controlled directly, while in other embodiments, hot air may besupplied continuously to the tube but is not allowed to impinge on theprecursor or other portions of the fabricated article via anothercontrol method. In FIG. 148(a), an inter-layer junction precursorsimilar to that in FIGS. 147(a), 147(b), 147(c), and 147(d) is locatedbeneath a cluster comprising a hot air tube (which may be equipped withan outlet nozzle, not shown), and a delivery tube containing solder inwire form. The method may however be used to solder intra-layerjunctions. In the embodiment shown, the tube is equipped with a sideport for vacuum. In FIG. 148(b), vacuum is applied to the vacuum portwhile hot air is supplied to the tube. As a result, hot air does notissue from the bottom of the tube, but is diverted substantially throughthe vacuum port.

In FIG. 148(c), solder wire has been pushed out of the delivery tubesuch that a portion of the solder is between the hot air tube and thewires to be soldered. Simultaneous with pushing out the wire or justafterwards, the vacuum port can be switched off as in FIG. 148(d), thusallowing a jet of hot air to issue from the tube and impinge on thesolder and precursor wires. In some embodiment variations, the jet maybe allowed to first pre-heat the wires, before the solder wire isintroduced. Shortly after the solder is heated by the jet, a drop ofsolder melts and detaches from the wire, where it is blown towards thewires in the precursor and envelopes them as shown in FIG. 148(e).Vacuum can be applied again to the vacuum port to divert the hot air,allowing the solder drop to cool, and forming a junction (alternatively,the cluster can be moved).

In some embodiment variations, a moveable vane (which may include asmall hole) may be located between the hot air tube and the solder wire,such that moving the vane can control the flow of hot air. This may beused in lieu of vacuum. In some embodiment variations, in lieu of solderwire, solder in ball form may be delivered (e.g., by a tube) into theair stream. In some embodiment variations, flux if required may beincorporated into the solder (e.g., in a core of the wire), while inother embodiment variations, flux may be applied to the wires bydispensing through a dropper/pipette, jetting, brushing, or other means.

In some embodiments, solder may be delivered as preform (ball, foil, orother shape) to the wires to be joined, and reflowed by hot gas,contact, laser, or other methods. In some embodiments, the wires to bejoined may be pre-coated with solder, in which case a source of heat andin some cases, a slight pressure to bring the wires into contact, cansuffice to create a joint. In some embodiments, solder wire may beencapsulated in the extrude alongside the wire (e.g., copper) serving asan interconnect or other element. The co-encapsulated solder wire (whichmay be delivered adjacent to the other wire through a suitably-shaped(e.g., slot-shaped) capillary), may be placed in locations only whereneeded, or may be placed alongside and co-encapsulated with the otherwire in general. In a cavity or other region where a junction is to beformed, the solder wire is melted to form the junction. Not all wires ina junction may require adjacent solder wire, but in these embodimentssolder wire would be adjacent to at least one wire.

FIGS. 149(a), 149(b), and 149(c) depict plan views of intra-layerjunctions used in some embodiments. In FIG. 149(a), two wires are madeto cross one another (at 90 degrees or another angle) on the same layer;the lower wire may be displaced downwards slightly when the second wireis laid. As shown, the wires are incorporated into the extrudate ofmatrix material, the flow of which is interrupted in the central regionso as to provide bare wires. Extrudates of pure matrix material can beprovided alongside these composite extrudates as shown. In someembodiment variations, conductive material can be placed at theintersection of the wires, enveloping them. In other embodimentvariations, the wires may be directly joined by heating them (e.g.,laser welding, resistance welding). FIG. 149(b) depicts two wires whichhave been brought into close proximity—which may facilitate forming ajunction—by producing bends in them. In the case shown, the wires eachbend 90 degrees; however, smaller bend angles are also possible. In FIG.149(c), the relatively small gap between the wires has been filled byconductive material (e.g., solder).

In some embodiments, motions of the capillary during encapsulation ofwire (or variable wire heating) may be used to shift the wire positionwithin the extrudate to one side or the other, reducing the inter-wiregap for intra-layer junctions, or shift it up or down in the extrudate,reducing the gap for inter-layer junctions.

Some varieties of conductive material used in junctions (or magneticmaterial used in magnetic structures) such as certain ECPC and SMPCformulations may be difficult to dispense using an extruder due to highviscosity, segregation of polymer binder and powder, etc. In such cases,small pre-measured quantities of material can be loaded into smallcompartments in a replaceable carrier and delivered to a junction asneeded by merely pushing them out (with some heating of the material andin some cases, the wires, provided). FIG. 150 depicts a 3-D view of adisk-shaped carrier with a series of holes which can be filled withmaterial. If a hole is positioned over wires, material in the hole canbe pushed out (e.g., by a pin) to contact the wires and form a junction.In the figure, the disk is designed to be spun slowly using a centralhole for an axis and translated. With the material holes arranged in aspiral pattern as shown, any hole can therefore be placed in the desiredlocation. Other arrangement of holes or other compartments for materialmay be created, including rectangular arrays, narrow strips/tapes, etc.

In some embodiment variations, to soften the material before ejection(or even cause ejection by sufficiently melting it, obviating the needfor a pin), heaters may be embedded in the carrier adjacent to eachhole. For example, the carrier may be made using printed circuit boardtechniques and electrodes fashioned from copper on each side of eachhole. Once a hole is in position, probes can make contact with theelectrodes and heat the material in the holes directly through resistiveheating, or indirectly if a resistive heater (e.g., nickel-chromiumfilm) is provided adjacent to the holes. In some embodiment variations,the conductive material may be in the form of a continuous filament(e.g., circular or flat/ribbon-shaped in cross section). A portion ofthe filament when positioned over a junction precursor can then bebroken off and “stamped out” by a moving element, pushing it into acavity in the precursor and surrounding the wire. Similarly, conductivematerial may be provided in the form of a thin sheet and sections of thesheet punched out using a moving punch or “cookie cutter”.

In some embodiment variations it may be desirable to continuously andglobally heat the carrier so that the material is in a state ready forejection and able to flow around the wires when forming junctions.

A requirement for some wearables, soft robotics, and other devices isnot just flexibility, but stretchability. Thus stretchable interconnectsmay often be needed. The matrix material may be a highly stretchablematerial such as a thermoplastic or silicone elastomer with elongationson the order of 1000%. However, the elongation of straight metal wire isminimal. On the other hand, wire that is bent into a serpentine, zigzag,or other non-linear shape will be bent into a new shape when stretched,rather than be immediately put into tension. Wire interconnects can thusbe incorporated into stretchable (e.g., elastomeric) structures usingFEAM by forming the wire into non-linear shapes. FIG. 151(a) depicts a3-D view of a stretchable elastomeric block with corrugations whichallow it to be stretched with a relatively low force when the ends arepulled. Within the block as shown in the 3-D views of FIGS. 151(b) and151(c) is a length of wire in a zigzag pattern. The wire continues topass through the two ends of the block to form leads. Within the blockthe wire passes through anchor regions where the corrugations from topand bottom of the block converge. The wire also passes through postslocated along the long sides of the block, to which the wire istemporarily anchored during the FEAM process, allowing the wire to bendsharply. When the block is stretched sufficiently, beyond the pointwhere the posts can merely deflect, the wires break free of the posts(they are intentionally anchored only weakly by surrounding matrixmaterial) and each “V” shaped section of wire, the vertex of which hadbeen secured to a post during fabrication, now is free to extend,allowing a great increase in the length of the block without putting thewire into tension. Moreover, the corrugations divide the blockinternally into small transverse compartments, each of which containsone wire section. Thus wire sections are isolated and cannot becometangled with one another when tension on the block is released and thewire is forced to reshape itself to fit the compartment. Moreover, ifthe corrugations are formed at an angle to the horizontal exceedingapproximately 45 degrees, there is no need for support material withinthe block.

FIGS. 152(a), 152(b), and 152(c) depict 3-D views of another stretchableblock, shown with top and bottom in FIG. 152(a). In this case, the blockcontains a hollow volume (caps on the long sides are not shown, forclarity), within which is a non-linear wire (here, a zigzag). As can beseen in FIGS. 152(b) and 152(c), the wire is attached to pillars whichare themselves attached to the bottom of the block. If a serpentineshape is desired for the wire, more pillars can be used to providetemporary attachment points for the wire during the FEAM process. If theblock is stretched a small amount, the pillars can deform inwards(especially if not also attached to the top of the block), allowing thewire to form a zigzag with a smaller “amplitude” and increased“wavelength”. With a greater degree of stretch, the wire can pull freeof the pillars and straighten out entirely if needed. It is preferablein some embodiment variations that the pillars are indeed attached tothe top as well as the bottom so that when the block is allowed toshorten, the wire cannot snag on a pillar, which may cause breakage thenext time the block is stretched.

The 3-D views of FIGS. 153(a) and 153(b) depict a similar structure tothat of FIGS. 152(a), 152(b), and 152(c), but in which the side caps arevisible (and the top is removed to allow the inside to be seen), and thepillars are replaced by flexures which are attached to the caps. In thisembodiment, stretching the block causes the flexures to stretch, suchthat the wire can achieve a lower amplitude and longer wavelengthwithout breaking free (although it may still be free to do so if theblock is stretched excessively). The caps themselves may deform somewhatwhen tension is applied to the flexures by the wire. The top and bottomand/or the caps may be corrugated to facilitate a greater degree ofstretching.

The 3-D views of FIGS. 154(a) and 154(b) depict another approach toproviding a stretchable interconnect. Here, a portion of the wire awayfrom its ends (e.g., in the middle) is wrapped both clockwise andcounterclockwise around a “spool” and anchored to the spool between theclockwise and counterclockwise windings. The spool is supported so thatit is free to twist around its longitudinal axis. In the figures, thespool supports comprise a set of thin flexible rods; however, spiral orhelical springs (e.g., of two different handedness) printed in flexiblematerial, and other twistable structures may be used. When the unwoundportions of wire are put into tension, the spool is forced to rotate inthe direction shown, unwinding wire from the spool in both directions,thus allowing the wire to lengthen. When tension is released, the spoolthen rotates in the opposite direction, “reeling in” the wires. Ineffect, the spool acts as a retractable reel. The entire structure canbe fabricated using FEAM.

Approaches to allowing stretchability such as those in FIGS. 151(a),151(b), 151(c), 152(a), 152(b), 152(c), 153(a), 153(b), 154(a), and154(b) which incorporate extra wire within the printed structure, canalso be used to allow for inter-layer interconnects/junctions. If thereis extra slack available in a wire on a given layer A and access isprovided to it through a channel or other opening, then on a subsequentlayer B, a portion of the wire on layer A can be pulled through theopening and brought vertically or at another angle through the structureto arrive at another layer, where it can for example be joined to a wireor component pad on layer B.

FIGS. 155(a), 155(b), and 155(c) depict 3-D views of the front of theWDS (a.k.a., wire feeder/cutter) such as that shown in FIGS. 139(a),139(b), 139(c), 139(d), 139(e), 139(f), 139(g), and 139(h). Thedownstream capillary typically must extend past the end of the baseplate. However, if the capillary is thin, it can readily be deflected bytension on the wire (once the wire is anchored within the fabricatedlayer), which can have a deleterious effect on horizontal wirecentering. Therefore, it is desirable to stabilize the capillaryhorizontal position (the vertical position may also be important tostabilize). In FIGS. 155(a) and 155(b), guy-wires have been addedbetween the base plate and the distal end of the capillary. When intension, the guy-wires minimize capillary deflection, yet do notinterfere with printing. Alternatively, as in FIG. 155(c), at least onegusset (two are shown) may be bonded (e.g., welded) to the capillary tostabilize it. In lieu of gussets and guy-wires, the capillary itself canbe fashioned from plates (e.g., two grooved plates, or one grooved plateand one flat plate) which sandwich the wire; such plates are muchstiffer and therefore more resistant to horizontal bending. Since thecapillary cannot be as small on its interior as the wire, there isalways some clearance between the two, which may allow the wire positionto change within the extrudate. This can be addressed in someembodiments by slightly underfeeding the wire (i.e., feeding it at alower speed than the tangential speed of the nozzle) so as to keep it inmild tension.

FIGS. 156(a), 156(b), 156(c), and 156(d) depict in elevationcross-sectional views a sequence for backfilling a printed cavity with apowdered material, such as creating a soft magnetic structure usingpowdered iron or steel. In some embodiment variations, a cavity can befilled with powder only (then capped), while in other embodimentvariations, the cavity can be filled with a liquid as well as a powder(then capped), while in still other embodiment variations, the cavitycan be filled with a solidifiable material which binds the powder, aswell as a powder (then capped or left open). Suitable solidifiablematerials include thermoplastic and thermoset materials, photo-cured(e.g., UV-cured) materials, adhesives, etc. For example, low-viscositywaxes (e.g., paraffin, beeswax, Crystalbond 555 (Aremco Products Inc.,Valley Cottage, N.Y.)) may be used, as well as higher-viscositythermoplastics. Thermoset materials such as two-part epoxies andurethanes (typically low viscosity) can also be used, as can gellingmaterials and agents such as gelatin or agar solution, and heat-settingmaterials such as albumin. In the case of materials such as urethaneswhich require mixing two or more parts together, it is problematic toincorporate in a FEAM system a mixer which combines the materials whilein contact with system components. This is because if use of thematerials is intermittent (as it would be for creating magneticstructures), then unless those components are cleaned/flushed soon aftermixed material has contacted them, the material can solidify and makethem unusable. Therefore, point-of-use, non-contact mixing is highlydesirable.

The cavity is shown in FIG. 156(a), while in FIG. 156(b) three deliverytubes are shown having moved so that two of them are above the cavity.These two tubes are intended to deliver parts A and B of a two-partsolidifiable liquid such as a quick-setting hard or elastomericurethane. Mixing may be accomplished in at least two ways. In the first,liquids A and B merely fall into the cavity and intermix within it. Inthe second, as shown in FIG. 156(c), liquid streams or drops (e.g., ifthe liquid has been jetted using pulsed/drop-on-demand or continuous jetapproaches) A and B collide in mid-air en route to the cavity. Thecollision encourages intermixing such that the liquid entering thecavity is already reasonably mixed, and depending on setting time,inter-diffusion can accomplish the rest. If the Reynolds number is highso the flows are turbulent even before collision, additional mixing mayoccur. After filling the cavity with mixed liquid, a dispenser such as atube equipped with a screen (as depicted) or cap at it lower end andfilled with powder is positioned above the cavity. Vibrating or shakingthe tube horizontally and/or vertically allows powder to be dispensedthrough the screen, as would briefly opening a cap. Powder entering themixed liquid, assuming low enough viscosity, can settle to the bottom ofthe cavity due to its higher density, forming a reasonably densesediment.

The method of FIGS. 156(a), 156(b), 156(c), and 156(d) is not limited tomaterials mixed from multiple (two or more) parts, and can be used withsingle-part materials such as waxes which are introduced while hot andlow viscosity, then allowed to harden as they cool, etc. In someembodiments, binders with high surface tensions and which are allowed toevaporate can help pull particles together into a compact, high-densitymass. The method of FIGS. 156(a), 156(b), 156(c), and 156(d) can beperformed with cavities that are of the desired depth, or with cavitieswhich are gradually printed and filled (e.g., one or a few layers at atime).

FIGS. 157(a), 157(b), 157(c), and 157(d) depicts in cross-sectionalelevation views a method for incorporating solid objects such as ballsfor built-in ball bearings (assumed here), magnets, balls of conductivematerial such as ECPC, solder preforms, electronic components, etc.within a printed structure. Useable ball bearings (e.g., for rotarymotors) can be built using FEAM by incorporating such balls in raceswhich are lined with hard or lubricious fibers/wires (similar to FIGS.76(a), 76(b), 76(c), and 76(d)), are made from hard (e.g., filled)polymers, etc. In FIG. 157(a), a cavity has been left in a printedstructure (typically one only partially built). Above the cavity hasbeen positioned a dispenser filled with balls. The dispenser has anoffset opening at its bottom, and a moveable pin/plunger which can pushballs above the opening (FIG. 157(b)) and allow them to fall out of thedispenser (FIG. 157(c)). If friction is inadequate to prevent balls frommoving above the opening on their own, a flexure can be provided whoserestraining force is overcome by pin motion. In FIG. 157(d), the pin hasretracted, allowing the next ball to come into a position (via gravityor a spring) where it can be dispensed by the next movement of the pin,once the dispenser has moved to another position. In addition to balls

In some embodiments, a method for producing magnetic structures may beused which involves dispensing small, solid pieces of magnetic materialof standardized shape and arranging them to form a volume of the desiredshape. These pieces, or blocks, can in some embodiment variations fill acavity, or be held together by a binder/matrix which is applied to themor around them. For example, to create a solenoid plunger/core, a cavitycan be created in the printed structure, and small space-filling ornearly space-filling blocks of iron or other soft magnetic material canbe introduced into the cavity. A dispenser similar to that of FIGS.157(a), 157(b), 157(c), and 157(d) may be used, or other dispensers orpositioners may be used (e.g., pick and place approaches using vacuumcups, electromagnets, etc.). One example of a space-filling structurethat could fill a rectangular cavity of suitable dimensions is a cube(e.g., 1 mm on a side), and if the cavity is deeper than the side of thecube is long, multiple “layers” of cubes may be inserted into the cavityuntil it is filled. If cavities normally have standardized or minimumdepths (e.g., if solenoids are always made with plungers of a certainaxial length), widths, or lengths, then shapes which are not equiaxedsuch as rectangular, triangular, or hexagonal prisms may allow for moreefficient packing. Dimensions of blocks may be made to be integermultiples of layer thickness, although accommodation may be made forbinder or adhesive thicknesses. In the case of a solenoid, since themagnetic flux is axial, it is desirable to use elongated blocks whichare arranged parallel to the solenoid axis, minimizing air gaps alongthis axis which increase reluctance.

In some embodiment variations, shapes may be provided in continuous form(e.g., a wire or rod) and are cut to fit as they are dispensed. In someembodiment variations, if a shape is not itself space filling, and ahigh volume fraction of the material comprising the shape is desirable,then multiple polyhedra which together are space-filling may be used(e.g., tetrahedra and octahedra). In some embodiment variations,deposited blocks may be simply placed and then captured in the desiredconfiguration by capping a cavity or depositing material around them. Inother embodiment variations, blocks may be bound by applying abinder/adhesive to them as they are placed (e.g., via roller, brush,dipping, or spray), be manufactured with surfaces coated with adhesive(a pressure-sensitive adhesive, an adhesive that is activated duringdispensing, etc.), coated with solder or a heat-activated adhesive suchas low-viscosity epoxy so they can become bound together (they can bebriefly heated as deposited by a laser, for example), be manufacturedwith mechanical interlocking features (e.g., such as LEGO® blocks), etc.In other embodiment variations, they may have features such asre-entrant “arrowheads” at their lower ends, and pressed into the cavityor on a surface of a layer while hot such that the lower ends penetrateinto the material below them (assuming it is reflowable such as athermoplastic) and capture the blocks, or an adhesive layer may beapplied to the cavity bottom or layer surface to bind the blocks fromtheir lower ends. In other embodiment variations the blocks can includefeatures which lock onto wires which are exposed below or around them,or can be soldered to them. In yet other embodiment variations, they maybe bound by placing them and then infiltrating them with a preferablylow-viscosity binder, which may wick into small gaps between the blocksvia capillarity, or inserting them into a cavity filled with a liquidbinder. In such cases, the blocks may be provided with modified shapeswhich don't completely fill space, and which allow for infiltration(e.g., grooves or textures on surfaces, radiused or chamfered edges). Insome embodiment variations, blocks are not bound, but simply placed in acavity which is then capped (e.g., by depositing more structuralmaterial over them), capturing them.

FIGS. 158(a) and 158(b) depict elevation cross-sectional views of apiloted, normally-closed solenoid valve that may be produced with FEAM.A piloted valve can handle high pressures yet be actuated with arelatively low force solenoid. In FIG. 158(a), the solenoid plunger isdown, held there by both a lower and upper elastomeric element. In thisposition, the plunger blocks the pilot hole of a diaphragm which restson an annular seat, such that the valve is closed. When the solenoid isenergized, the plunger need only provide enough force to lift theplunger off the pilot hole in the diaphragm, after which fluid pressurewill equalize on both sides of the diaphragm, lifting it and allowingfluid to flow through the channel (FIG. 158(b)).

FIGS. 159(a), 159(b), 159(c), 160(a), 160(b), 160(c), 161(a), 161(b),161(c), 161(d), 162(a), 162(b), 162(c), 163(a), and 163(b) depict 3-Dviews, some in cross-section, of fluidic actuators which may be producedmonolithically with FEAM, using elastomeric materials and in some cases,rigid materials. Temporary, preferable easily removable (dissolvable,friable, and/or meltable) support materials may also be used duringfabrication. The actuators can use valves of the kind shown in FIGS.158(a) and 158(b), and may use two in a valve assembly, for example: onefor inlet and one for exhaust. Actuators may be combined together, andmay share common inlet plumbing (e.g., a common pressure source) andexhaust plumbing; in some embodiments plumbing may be integrated intothe device. Some actuators incorporate rigid plates or other elements attheir ends or elsewhere as part of the design.

In FIGS. 159(a), 159(b), and 159(c) a bending actuator is shown. On oneside of it is a wall which is minimally extensible, and may containfiber/wire reinforcement (in the case of wires, they may serve a dualpurpose in also transmitting signals through the device, e.g., tocontrol a valve in another device). On the opposite side is acorrugated, bellows-like surface. Between the two is a chamber which isfilled with fluid, causing bending away from the bellows side as shownin the finite element analysis simulation of FIG. 159(c).

FIGS. 160(a), 160(b), and 160(c) show an extending actuator which growsin length when inflated, as shown in the simulation of FIG. 160(c).FIGS. 161(a), 161(b), 161(c), and 161(d) show a shortening/contracting,muscle-like actuator, somewhat similar to a McKibben air muscle, butusing either no reinforcing fibers or longitudinal ones. FIG. 161(b)shows the muscle with multiple axial fibers arranged circumferentiallyaround the device; two of these fibers can be seen in the sectional viewof FIG. 161(c). FIG. 161(d) shows a simulation (top) of the devicewithout fibers when inflated, while the bottom simulation shows thedevice with fibers when inflated.

In FIGS. 162(a), 162(b), and 162(c) a rotary actuator is shown. Thedevice comprises at least two extension actuators similar to those ofFIGS. 160(a), 160(b), and 160(c) (though two shortening actuators likethose of FIGS. 161(a), 161(b), 161(c), and 161(d) may alternatively beused) but with curved longitudinal axes. The valve assemblies of theactuators are fixed to plate A, and the actuator creates a rotation ofone plate (plate B) relative to another (plate A) by applying forces tothrust plates attached to plate B (FIG. 162(b): a section view withPlate B removed). The two actuation units can work in “parallel”creating larger torque, or antagonistically, creating the ability ofreversing the rotation as well as adjusting the rotational stiffness.The range of motion can be extended by stacking several actuators asseen in FIG. 162(c). The central flexible tube (which allows fortwisting) allows for pressurized air and valve control signals to betransmitted to serially-connected actuators of the same or differentconfiguration.

FIGS. 163(a) and 163(b) depict a group of actuators such as those ofFIGS. 160(a), 160(b), and 160(c) (though two shortening actuators likethose of FIGS. 161(a), 161(b), 161(c), and 161(d) may alternatively beused) to form a three degree-of-freedom device which can both tilt plateB in any direction relate to plate A by different angles, or change thedistance between plates A and B. FIG. 163(b) depicts a simulation withplate B tilted. The central tube, flexible to allow for bending andchanges in length, also allows air and signals to be transmitted furtheron.

FIGS. 164(a) and 164(b) depict a dual-direction bending actuator withtwo chambers separated by a minimally extensible wall (forming a“spine”), allowing bending in a plane in either direction (whereas theactuator of FIG. 159 only allows bending in one direction). Actuatorsable to bend in any direction (not just in a plane) can similarly befabricated, using three or four actuators surrounding a minimallyextensible central core. The actuator may be provided with an optionalcap (FIG. 164(b)).

FIG. 165 shows an actuator fabricated in a hollow, twisted shape. Wheninflated, the rigid plate at the top untwists itself through a smallangle as shown, with a minimal change in overall length of the actuator.

FIG. 166 depicts several of the actuators described above, joinedtogether to form a robot arm. Joining may be done after fabricating eachmodule separately, or the entire arm may be monolithically fabricated.

In the elevation view of FIG. 167, a solenoid is shown in which thewindings on each layer are joined together by a conductive material suchas solder or ECPC, and the junctions are staggered from layer to layer.The conductive material should not extend too much past a layerjunction, so as not to interfere with depositing the next layer or riskshorting to an adjacent wire.

FIGS. 168(a), 168(b), 168(c), 168(d) 168(e), 168(f), 168(g), 168(h),168(i), and 168(j) depict a number of 3-D views of a WDS fordifficult-to-cut fiber (e.g., flat steel wire used to make soft magneticstructures) with some similarities to that of FIGS. 144(a), 144(b),144(c), 144(d), 144(e), 144(f), and 144(g). However, this WDS uses arotating blade (e.g., a non-slotted thin diamond dicing saw from DiscoHi-Tec America, Inc., Santa Clara, Calif.) to cut the wire. Such bladesmay be very thin (e.g., 100 μm) and normally have a surface coated withfine diamond. In some embodiments, blades made from other materials(e.g., abrasive cut-off wheels) may be used, and in some embodiments,the blades may be toothed or slotted. In some embodiments, coolant(e.g., rapidly-evaporating liquid or water) may be provided. In someembodiments, debris released by cutting may be collected by a vacuumnozzle or other structure, be collected by sticky “flypaper”, etc. FIG.168(a) is an overview of the WDS, which has a feeding subsystem based onrollers similar to that of FIGS. 144(a), 144(b), 144(c), 144(d), 144(e),144(f), and 144(g), which FIG. 168(b) is an overview of the wire cuttingand binding portion of the WDS. The WDS shown in the FIGS. 168(a),168(b), 168(c), 168(d) 168(e), 168(f), 168(g), 168(h), 168(i), and168(j) includes an extruder as well, which provides a binder to attachwire segments to one another and surrounding materials. The binder maybe a thermoplastic material, in which case the extruder may be filamentfed, or be a screw extruder similar to that of FIGS. 145(a), 145(b),145(c), and 145(d). Or, the extruder may extrude an adhesive or paste.Possible binders include hot melt glues (e.g., if formulated foradhesion to the fiber and in some embodiments, surrounding materials),cyanoacrylates, UV-cured epoxies, etc. The extruder in some embodimentsis mounted to a support which is moved on a carriage by an actuator suchas an air cylinder. This allows the extruder to retract while a cutsegment of wire (or other fiber) is positioned below the nozzle. Shieldsmay be provided to protect personnel from cutting-produced debris orblade fragments (if the blade fractures).

FIGS. 168(c), 168(d) 168(e), and 168(f) are views focusing on thecutting blade and related hardware. The blade is rotated by a motor atsignificant speed. The blade and motor are both translated by amotorized cutting stage such that the blade can be moved across thewire, cutting the wire with a motion similar to a radial arm saw. Thewire is pushed by the feeding subsystem through a groove in a wireguide, which has a cover at its bottom to prevent the wire from fallingout of the groove (however, if the wire is magnetic, it may also beretained magnetically in some embodiments): the guide and cover serve asa capillary. As shown best in FIGS. 168(i) and 168(j), the wire passesacross a region of the guide that is slotted to allow the blade tocompletely transect the wire as it moves across. The blade may berotated in the direction shown or in the opposite direction. Cutsegments of wire are directed beneath the nozzle of the extruder. Oncecut, there may be a slight burr on the wire, or a slight bend in thewire, which interferes with insertion of the wire into the downstreamcapillary/wire guide. This can be corrected in some embodiments bywithdrawing the wire into the capillary/wire guide section just upstreamof the dicing blade (or for the feeder/cutter of FIGS. 139(a), 139(b),139(c), 139(d), 139(e), 139(f), 139(g), and 139(h), the descendingblade) so that the burr and/or wire is bent/shaved.

The 3-D views of FIGS. 169(a), 169(b), 169(c), 169(d), 169(e), and169(f) depict a ring similar to that of FIG. 83, in which the capillaryis supported by guy-wires. The ring may contain wire arrangedcircumferentially within, and thus serves as a wire dispenser. The ringcan rotate around the nozzle so as to orient the capillary tangent tothe nozzle path, for example. The guy-wires may be passive, or beactively tensioned (or the nominal tension reduced) so as to move thetip of the capillary as needed. For example, the tip of the capillarymay need to be retracted as in FIGS. 30(a), 30(b), and 30(c), in whichcase both guy wires may be pulled inwards, lifting the tip, or in someembodiments, the ring itself may be lifted. Or, if the tip is to bemoved horizontally (e.g., to better center the wire in the extrudate,e.g., while the extrudate curves in one direction), then the guy-wire onone side of the capillary can be pulled inwards while that on theopposite side can be played out. Thus the tip of the capillary, whichnominally can be deflected from its natural shape by tension in theguy-wires, can be controlled to move in both the vertical and horizontaldirections. Stepper motor-driven linear actuators, etc. may be used tocontrol the guy-wires.

In FIG. 169(a) and in the section view of FIG. 169(b), the ring,capillary, and guy-wires are shown. In FIGS. 169(c) and 169(d), anextruder with its nozzle has been inserted, with the nozzle orificealigned to the axis of rotation of the ring. In FIGS. 169(e) and 169(f),additional extruders A-C (and/or other apparatus, such as solder pastedispensers, SMPC delivery systems, laser welding apparatus, etc.) havebeen added to the primary extruder, whose orifice is centered on thering axis. The additional extruders may be coupled together but whetherindividually controlled or clustered, are capable of moving vertically.Initially as in FIG. 169(e) the primary extruder may be extruding whilewire is fed through the capillary, so as to encapsulate the wire as inthe standard FEAM process. When this is done and it is time to employ atleast one of the extruders A-C, the ring rotates to one or more “safe”positions which allow extruders A-C to descend without colliding withthe capillary or guy-wires to the required height (which may vary withthe particular extruder (the stage moving extruders A-C may also be usedto focus a laser soldering system, etc.). Once descended, extruders A-Cmay operate normally. Before needing to encapsulate wire again, theextruders retract vertically, allowing the ring to rotate again withoutinterference. In some embodiments, additional extruders may be locatedoutside the ring. However, locating them inside the ring has the benefitof achieving reducing the space between the nozzles, allowing for alarger device to be printed which includes material from any of theextruders.

FIGS. 170(a), 170(b), and 170(c) depict several views of a method forfabricating a helical coil with a horizontal axis that minimizes thenumber of junctions needed (indeed, as shown the wire is continuous,with no junctions). The method involves fabricating the coil in aninitially flattened state, and then (optionally) expanding it so that itforms a shape suitable for a core or plunger to be inserted (this can befabricated alongside the coil, and then slid into place). As shown inthe elevation cross-section of FIG. 170(a), the coil is built from twolayers which are separated by a small gap, so that they are not fused.Layer 2 is produced without supports in some embodiments by virtue ofthe wire (under slight tension) within layer 2 providing a substratearound which extrudate can solidify (e.g., as in FIGS. 55(a), 55(b),56(a), and 56(b)). A small vertical section of the wire is providedbetween layers 1 and 2 to establish the required gap in someembodiments. The wire is continuous, but for clarity, wire on layer 1 isshown as a wide solid line, while wire on layer 2 is shown as a widedashed line; vertical sections are shown as narrow solid lines.

FIG. 170(b) is a 3-D view of the coil as-fabricated; only wire is shown;matrix material is not shown for clarity. However, matrix materialsurrounding the wire is in close proximity on adjacent windings andfuses together along the Y axis. The FEAM printhead (nozzle andcapillary) produces this coil by moving in X, Y, and Z, not merely X andY as usual. The result is a flat tube of matrix material within which isa (flattened) helical coil. As shown, the two ends of the coil can beextended to provide leads for electrically connecting the coil.

The coil may be used as-is (e.g., a narrow core or plunger may beinserted into it, or it may serve as an air core inductor or other coil.However, it may be expanded as in FIG. 170(c), after the coil has beenfabricated. This may be performed mechanically by pulling on it,inserting an object into it, or (if it is substantially free of leaksand closed at both ends by deposited material) by inflating it with afluid such as air. If the matrix material is capable of thermallysetting or is a thermoplastic or a photo-cured material, then onceexpanded, the expanded shape can be maintained by the application ofheat or light (e.g., UV). Indeed, hot gas may be used to both expand thecoil and set the new, expanded shape. The approach of FIGS. 170(a),170(b), and 170(c) may be used with either elastomeric or rigid matrixmaterials.

In general, structures may be 3-D printed in a flattened condition tosave printing time and/or obtain better strength, then inflated orotherwise reshaped into the final configuration required. If made fromthermoplastic materials, the application of heat can retain the newconfiguration.

FIG. 171(a) is a 3-D view of an elastomeric robotic arm comprisingbuilt-in actuation provided by specially-shaped and arranged electrodes.FEAM can produce dielectric elastomer actuators (DEAs) by embedding wire(e.g., round, square, flat/ribbon) within an elastomer. In the exampleshown, a large number of electrodes are provided to create acephalopod-like arm which can bend and change its length and stiffness.Also provided are touch sensors at the surface of the arm, and stretchsensors which can be used for proprioceptive feedback and control. Thesesensors may be piezoresistive, capacitive, inductive, or use othermodalities. As shown, certain electrodes are used to locally contractthe elastomer transversely, which causes a local expansion along thelongitudinal axis of the arm, since the elastomer volume is constant (ifan incompressible, vs. foam-like material). Other electrodes are used tolocally contract the elastomer axially, which causes a local transverseextension. A central channel provides space for wiring for theelectrodes, etc.

In FIG. 171(b), a close-up view of the end of the arm is provided, whileFIG. 171(c) shows a building block of the transverse electrodestructure. The structure comprises wires forming alternative positiveand negative electrodes. Electrodes of one type are which are connectedtogether by flexible (e.g., thinner) wires in pairs, allowing relativemovement of the electrodes, and these pairs may be connected by positiveand negative bus wire (not shown) running along the sides of theelectrode structure. Wires can be made thinner and more flexible asneeded by dynamically adjusting the force applied to the rollers in thewire feeder to squeeze the wire (if ductile), or thin wires may bejoined to thicker wires as needed. When a voltage is applied to thestructure, it contracts as shown. The wires also serve to limitcontraction along their lengths, such that most of the correspondingexpansion occurs perpendicular to the plane of the structure. As shownin FIG. 171(d), the structure of FIG. 171(d) may be stacked, as is thecase in the arm of FIG. 171(a). Here it may be appreciated that when thecontraction occurs, it results in an extension as shown.

FIG. 171(e) shows a building block of the longitudinal electrodestructure. The wires here are all shorted together by flexible wires (orflexible regions of the wire), such that all the electrodes form astructure with the same polarity. As shown in FIG. 171(f), the structureis then stacked and connected with alternating positive and negativepolarities. When energized, the positive and negative layers approachone another. This results in a simultaneous transverse extension asshown. The wires may be corrugated as shown so as to not restrictexpansion along their lengths in some embodiments.

FIGS. 172(a), 172(b), 172(c), 172(d), and 172(e) depict 3-D views of asubsystem for FEAM which includes the ability to deposit materials otherthan fiber and a primary matrix material, and to perform soldering(e.g., using a laser). The system as shown incorporates a filament-typeextruder (#1) for the primary matrix, a second such extruder (#2) forsupport material (e.g., polyvinyl alcohol), a syringe extruder for SMPC,and apparatus required for soldering (a solder paste dispenser and laseroptics (e.g., a fiber collimator and fiber connected to a fiber-coupledlaser diode). It also incorporates a microscope which for example can beused to determine the exact position of wires prior to junctionformation (allowing better targeting of the solder paste and/or laserspot) and inspect/document the junctions produced (providing in-situquality control); in some embodiments, automated computer visioncapabilities known to the art may be used for both alignment andassessment purposes.

With the goal of locating all the extruders and other elements in asmall space, the subsystem has certain elements (laser optics, solderpaste dispenser, and microscope in this case) mounted to a plate (the“front plate”) which is hinged through the use of a shaft and bearingsto another plate (the “side plate”). This allows access to theseelements for servicing, as well as to elements mounted to the plate (the“rear plate”) behind them. A stop is provided against which the frontplate can be securely fixed with a screw during normal operation.

The rear plate is adjustable in X and Y so that the orifice of extruder#1 can be aligned to the theta stage axis of the platform below; thetheta stage is provided as in FIG. 42 to re-orient the capillary. Asshown in FIGS. 172(a), 172(b), 172(c), 172(d), and 172(e), the rearplate is mounted to the large plate behind it (the “Z plate”) through apivoting mechanism best shown in FIG. 172(c), which allows translationof the Z plate along the X axis, but also pivoting around the X axiswhen adjustment screws best shown in FIG. 172(d) are moved, which causesa movement of the extruder orifice along the Y axis. Springs are used topre-load both directions of adjustment, as shown.

FIGS. 173(a), 173(b), and 173(c) are a sequence of plan views of aportion of an electronic circuit breadboard produced using FEAM. In FIG.173(a), a hole is provided for the insertion of the pin of an electronicdevice (or a wire or connector). A wire which is preferably somewhatspringy so it is pre-loaded against the pin (but could in someembodiments be annealed Cu or another soft material) may be embedded inpolymer (here, an elastomer) in most areas, but is exposed within thehole. It may be formed into a loop as shown so that it can contact theinserted pin on more than one side, or can be bent into a double,overlapping V-shape to contact the pin in four locations, etc. Prior toinserting the pin, in some embodiments the breadboard is stretchedlocally in the region of the hole (if elastomeric), e.g., by insertinginstruments into the stretch holes provided and pulling, as in FIG.173(b). This provides for a zero insertion force connection. The pin isthen inserted as shown. In FIG. 173(d), the elastomer is relaxed and thewire deforms around the pin. In some embodiments, no pre-stretching isrequired (or possible, if the dielectric is rigid), and the pin simplydeforms the wire as it is inserted. In some embodiments, the pin holemay be shaped differently than shown (e.g., round for flat leads). Insome embodiments, the device is stretched, but no stretch holes areprovided (e.g., the entire breadboard might be stretched for componentinsertion). In some embodiments, multiple wires may be inside the hole;these wires may be on the same fabricated layer or on different layers.In some cases, the inserted pin may also therefore serve as a junctionbetween such wires. Indeed, in some embodiments, intra- and orinter-layer junctions are formed between wires by inserting plain pinsor wires into holes.

FIGS. 174(a), 174(b), 174(c), 174(d), 174(e), 174(f), and 174(g) depictsectional elevation views of a lightweight, inexpensive fluidic(pneumatic or hydraulic) robot which may be printed entirely fromelastomer and which is capable of crawling on surfaces no matter whattheir orientation (e.g., the robot may crawl on the ceiling, wall,window, hull of a ship, airplane, etc.) and is capable of moving in anydirection on the surface. The robot comprises two or more blocks, eachequipped with a cup or similar arrangement (although a simple hole inthe block may suffice in some embodiments) on their bottoms. Blocks areinterconnected by bellows which can expand (or contract in someembodiments) when supplied with fluid. Blocks are provided with portswhich communicated with cups and a port for communication with thebellows (though this can be done directly, vs. through the block).Tubing (not shown) in connected to the ports to supply fluid to thebellows and supply or withdraw fluid from the cups. When fluid iswithdrawn from a cup, it adheres to the adjacent surface, while whenfluid is supplied to a cup, it detached from and is able to glide overthe surface with very low friction (as in an air bearing).

The robot moves using an inchworm gait, as depicted in the sequence ofFIGS. 174(a), 174(b), 174(c), 174(d), 174(e), 174(f), and 174(g), inwhich the arrows indicate the direction of fluid flow and the directionin which elements of the robot move. In FIG. 174(a), the robot isinactive, but in FIG. 174(b), fluid is withdrawn from cup port B,locking block B to the surface, while fluid is injected into cup port A.Next in FIG. 174(c), fluid is injected into the bellows port, causingblock A to move to the left while block B remains in place. In FIG.174(d), block A is locked onto the surface as well; fluid may continueto be supplied to the bellows as shown, or the pressure may be reducedin the bellows in preparation for a forthcoming step, shown in FIG.174(e). In the latter figure, fluid flow has been reversed in block B,causing block B to detach from the surface. In FIG. 174(f), fluid is letout of the bellows (if not already done), causing the bellows toelastically contract and advancing block B. In FIG. 174(g), fluid isremoved from both blocks, locking them to the surface. The process canthen repeat, starting again with the step shown in FIG. 174(b), causingthe robot to advance further. Other actuators other than bellows (e.g.,bending actuators such as FIGS. 159(a), 159(b), and 159(c)) may also beused to displace one block relative to another.

In FIG. 174(h), a robot with four blocks and four bellows (shown insection) is shown in plan view. Such a robot is able to move in anydirection by proper sequencing of the fluid flows. Movement can beeither strictly parallel to the X or Y axes, and may alternate betweenthese movements to move along a diagonal. Or, by adjusting the strokelength of the righthand vs. the lefthand bellows so they are unequal (byvarying time and/or pressure for bellows length changes), the robot canbe made to turn. In some embodiments, robots may have built-in pressureand vacuum pumps, with batteries, and so be self-contained.

FIGS. 175(a), 175(b), 175(c), 175(d), 175(e), and 175(f) depict 3-Dviews of an arrangement similar to that of FIGS. 169(a), 169(b), 169(c),169(d), 169(e), and 169(f), but which also includes a wheel supported bythe ring (in some embodiments the wheel (and capillary) may be supportedby a bearing surrounding the extruder nozzle, etc.). The previous layerof material is not shown. The wheel may be grooved as shown in FIG.175(f) such that it can fit over the solidified extrudate (shown asround, but which may have another shape) and cause the ring, which issupported by a low-friction bearing, to rotate as the wheel rolls alongthe extrudate, using the extrudate as a track and the wheel somewhatlike a caster. This keeps the capillary (and potentially other hardwaresuch as a cooling nozzle, a source of radiation used for curing, etc.)substantially tangent to the extrudate without using an actuator torotate the ring and may be a lower cost alternative. The wheel shouldpreferably be small and close to the nozzle, and may be cooled to helpsolidify the extrudate. Nonetheless, the extrudate cannot have a veryradius of curvature, since the wheel must fit on it, and there will be asmall error in how tangential the capillary is relative to the extrudatesince the wheel is aligning itself to the extrudate at a position offsetfrom the nozzle. In some embodiments, the wheel can reshape theextrudate, and help push it into the previous layer, improving adhesion.In some embodiments, the wheel is driven and actively swiveled, pullingalong the nozzle.

If the wheel is shaped as in FIG. 175(f), it cannot fit over extrudatenext to other extrudate. This situation can be often avoided by firstprinting extrudate containing wire on a given layer. After this, thering is raised, raising both the capillary and wheel out of the way, sothat the nozzle can print according to any desired toolpath. In someembodiment variations, the wheel can track the extrudate using smallprojections (e.g., as with a pounce wheel), or a groove can be formed inthe extrudate by a projection on the nozzle which can interface with aridge on the wheel. In these cases, the wheel does not require a groove.

FIGS. 176(a), 176(b), and 176(c) depict a method of producing anextrudate in which wire or other fiber is exposed on one or moresurfaces (e.g., for bearing surfaces, electrical connections, aselectrodes), such as those shown in FIGS. 76(a), 76(b), 76(c), and76(d). As shown in FIG. 176(a), the hot end of the extruder has twoinput ports. Into one port flows structural material, and into the otherport flows support material. Both materials may be reasonably mutuallyadherent when solidified. Assuming these materials are of highviscosity, and given the small dimensions and low flow velocity, theReynolds number is low, so the flows are laminar and minimalinter-mixing of the materials will occur at their interface. Thus, theextrudate issuing from the nozzle has structural material on one sideand support material on the other. If the extrudate encapsulates a wire(shown with rectangular cross section), a 3-material composite will beformed. Since one material is sacrificial, once it is removed, the wireis exposed along its length. In some embodiments, materials may bearranged to flow such that the interface between them is horizontal,thus allowing the top or bottom of the wire to be exposed. In someembodiments, the wire is textured (e.g., with axial/longitudinalgrooves) to better interlock it within the structural material. Tofacilitate interlocking of wire that is not fully encapsulated withextruded matrix material, in some embodiments the cross-sectional shapeof the wire can comprise re-entrant/undercut features (e.g., anhourglass-like shape), thus allowing the wire to be anchored securelywithin the solidified matrix, for example, on a sidewall or horizontalup-facing surface of a part. In some embodiments, large diameter wire(e.g., with a circular cross-sectional profile) can be captured bydispensing at least a portion of the wire bare (without matrix materialencapsulating it), and depositing extruded material along its sides,such that the profile is captured, but no material overlies the top,leaving it exposed (e.g., for use as a contact in a USB or PCB-like edgeconnector).

FIG. 177 depicts an arrangement similar to that of FIGS. 29(a) and29(b), but in which discrete objects, vs. continuous fiber, areintroduced into the extrudate by the capillary/feed tube. These objectsmay be solid or semi-solid, or made from a liquid which may be miscibleor immiscible with the extruded material. For example, balls for ballbearings used in printed electric motors may be deposited as shown inthe figure within a soluble support material, which when dissolvedallows the balls to move freely. Objects can be delivered through thecapillary/tube by gravity feed, fluid pressure, a push wire, vibration,etc. in some embodiments, rather than deliver objects through anexternal capillary, then may be delivered through the nozzle orificedirectly.

FIGS. 178(a), 178(b), 178(c), 178(d), and 178(e) depict a method fordetermining toolpaths for the FEAM process which involve fiber, based ongeometry created in computer aided design (CAD) software. In FIG.178(a), a curved shape representing the desired path for a wire in astructure is shown. If the wire is to be encapsulated on a horizontallayer, the shape is planar, but can be complex in 2-D. Such a structuremay be included in a CAD assembly along with other structures to beprinted in various materials. In FIG. 178(b), the shape has beenexported as an STL file, such that it is represented by a set oftriangles. The curved sides of the shape are represented as planar,rectangular facets, each subdivided into two triangles, and trianglesalso represent portions of the top and bottom surfaces. In FIG. 178(c),a computer has been used to slice the STL file, intersecting thetriangles with a horizontal plane that is partway up the sides (e.g.,halfway as shown). Vectors are then generated as shown in FIG. 178(c)and enlarged, in FIG. 178(d), determined by the intersection between theside triangles and the plane. Triangles at the top and bottom are notintersected and no vectors are thus derived. FIG. 178(e) depicts thevectors that would be obtained from a short, straight shape. Next, aprocess running on a computer performs two steps. In one, the short “endvectors” of known length (based on the specified width of the shapeas-designed, or other identifying characteristics) are disposed of Inthe other, in some embodiments one set of the remaining vectors, eitherleft or right, is disposed of, or in other embodiments in which thedesired vectors are defined by the centerline of the designed shape,final vectors shown by the bold vectors in FIG. 178(e) are derivedhalfway between the left and right vectors, then both left and rightvectors are disposed of. The surviving vectors then represent thedesired toolpath for the extrudate.

Rather than cut wire with a blade to segment it as described above(e.g., in conjunction with FIGS. 178(a), 178(b), 178(c), 178(d), and178(e)), wire segment feeders (WSFs) capable of delivering wire (orother fiber) segments of the required length to the nozzle may be basedon alternative designs. It is desirable that such WSFs are small andlightweight enough that they can be rotated around the nozzle, obviatingthe need to rotate the printed part during fabrication (e.g., using atheta stage as in FIG. 42). Avoiding part rotation 1) reduces thesensitivity of nozzle/rotation axis alignment; 2) allows for higherspeed motion due to the lower moment of inertia of an WSF versus aprinted part, X/Y stages, and theta stage; 3) allows the use of multipleFEAM printheads in a single system (e.g., to increase productivity bymaking many parts simultaneously on a common platform); etc.

In some embodiments, a WSF may involve scoring the wire (e.g., using ablade) but not cutting through it. When tension is applied to the (e.g.,using two pairs of rollers), the wire is broken. With ductile materialssuch as copper, distortions such as burrs may be especially likely ifthe wire is fully cut; such distortions can make re-threading the wireinto the downstream capillary difficult and unreliable, causing jamming.However, wires made from ductile materials, when tensioned, tend tostraighten and neck down in the region of the score before breaking,leaving no burrs and allowing reliable delivery. Non- or less ductilefibers (e.g., glass, carbon, steel, tungsten, nickel-chromium) can alsobe broken by the methods and apparatus described by exceeding theirultimate tensile strength, and the location of the break can becontrolled by scoring them in the location desired, since the score (asmall fracture, microcracks, and/or stress-concentrating geometry) willfail in tension before the fiber fails in unaffected areas. Comparedwith cutting, scoring wears the blade considerably less (to reduce weareven further, a ceramic or diamond blade may be used), can work forfibers considerably thicker and harder than annealed copper wire, suchas (for reinforcement) carbon, glass, and steel fiber, or metals such asnickel-chromium and tungsten, and is easier to perform while the fiberis in motion.

FIGS. 179(a)-(b) show 3-D views of a printhead comprising an extruder(with cold and hot end) and a WSF comprising a wire spool with wire, twosmall motors (e.g., two NEMA 8 stepper motors, the shafts of which serveas drive rollers (in some embodiments separate drive rollers are used),two idler rollers (or in some embodiments, two additional motors) whichtogether with the motor shafts pinch the wire with a controlledpressure, a horizontally-sliding (in some embodiments blade motion is inanother direction) scoring blade (or other element able to locallydamage the wire (such as a rotating roller which moves to engage thewire and has a protruding blade or boss; this allows the wire to bescored without pausing while the roller tangential speed matches thewire speed), and three capillaries: downstream, upstream, and center,all of which may comprise, for example, stainless steel hypodermictubes. The downstream capillary delivers wire to the nozzle, while thecenter capillary is notched (or made from two pieces, possibly with ananvil) to allow access of the blade to the wire, whereas the upstreamcapillary guides wire from the spool. In some embodiments center andupstream capillaries may be combined into one capillary that is notchedon both sides to allow roller access, while in other embodiments inwhich wire/capillary friction is low, a single notch and a single driveroller may be used. Not shown are mounting and adjustment elements(e.g., to support idler rollers and adjust the wire guide positionrelative to the nozzle), the blade actuator (e.g., solenoid or aircylinder), an actuator to rotate the WSF around its axis of rotation(e.g., coincident with the center of the nozzle orifice), slip rings (ifapplicable) to supply power to the motors at any WSF orientation, acooling nozzle to rapidly cool the extrudate (e.g., etc., located 180degrees opposite the downstream capillary, and supported so as to rotatewith the WSF), apparatus used to heat the wire (if applicable), etc.

Each motor shaft and idler roller form a roller pair: one upstream andone downstream. As is shown better in the closer 3-D views FIGS. 179(c)and 179(d), the blade may be angled as shown so the point of contactwith the wire moves as it scores the wire through the notch in thecenter capillary, providing more efficient cutting and reducing localwear. In some embodiments the wire spool may be horizontal (i.e., have avertical rotation axis) and in some embodiment variations the spool maysurround the extruder. The spool may be oriented at other angles aswell. In some embodiments, multiple WSFs may surround a single extruder(e.g., three WSFs 120 degrees apart) so that multiple filaments (e.g.,round copper wire, flat copper wire, glass fiber for reinforcement) canbe introduced into the extrudate: the angle of the multiple-WSFsubsystem would be adjusted so that the active WSF is made tangent tothe nozzle path, for example).

The downstream capillary of the WSF (or capillaries in the case ofmultiple WSFs)—or else the entire WSF—should be able to be lifted by ashort distance when not needed so that the capillary does not collidewith materials already deposited on the layer.

FIGS. 180(b), 180(c), 180(d), 180(e), 180(f), and 180(g) depict in planview a sequence of steps in delivering a wire segment with the apparatusof FIGS. 179(a), 179(b), 179(c), and 179(d), while FIG. 180(a) shows allcomponents of the apparatus with the wire about to be fed toward thenozzle. In order to feed a wire segment through the three capillaries,both pairs of rollers turn at the same speed as shown in FIG. 180(b). Inthe position shown in FIG. 180(b), the distal/downstream end of the wireis in a position to be encapsulated by matrix material issuing from thenozzle if further fed by the rollers, or passively pulled through thecapillaries. When the control system, based on design data, determinesthat the currently-dispensed wire segment is to be terminated and thusthe wire is to be severed, the rollers briefly stop and then in someembodiments are rotated so as to feed wire in opposite directions. Or,as shown in FIG. 180(c), the downstream roller, if provided with a meansof slipping (e.g., reduced current, a low friction surface contactingthe wire, a slip clutch) may rotate so as to pre-tension the wire, ifdesired. (e.g., especially if there is nothing to stop the wire frommoving during scoring). The blade is then advanced through the notch toscore the wire as in FIG. 180(c) while the wall of the central capillaryopposite the notch prevents the wire from moving excessively. The bladeis then retracted, as shown in FIG. 180(d). Scoring can be performedwhile the wire is not advancing through the capillary, or in someembodiments while it is.

In FIG. 180(e), the scored wire has been optionally advanced furtherdownstream within the center capillary by the rollers so that the scoreis downstream from the region of the notch when it breaks; this canminimize the risk of a distortion in the wire interfering with feeding(e.g., a burr catching on the edge of the notch). If both upstream anddownstream rollers rotate with the same tangential speed, tension in thewire will not be low or zero, and so the wire will not prematurelybreak. In FIG. 180(f), the wire is tensioned and (possibly afterstretching and necking) broken in the vicinity of the score—its weakestpoint—by rotating the downstream rollers, or in some embodiments thedownstream/distal end of the wire is anchored in the part and thedownstream rollers turn passively or are disengaged while the upstreamrollers are stopped (or rotated to feed wire upstream, in the oppositedirection). In FIG. 180(g), the wire has been broken into two pieces: asegment and the remainder of the wire upstream of it. The segment hasmoved further downstream while the nozzle has advanced relative to theprinted part, while the tip of the remaining wire is positionedsimilarly to the wire in FIG. 180(b), thus allowing the process torepeat. Movement of the segment can be the result of being pulledpassively through the capillaries, or being pushed along by theadvancing tip of the remaining of the wire. Depending on their lengthsand the length of the capillaries, multiple wire segments can beproduced and stored within the center and/or downstream capillaries,ready for delivery. To minimize the risk of segments fallingspontaneously out of the downstream capillary (e.g., due to vibration),frictional elements may be added to the capillary such as small leafsprings within the capillary lumen, elastomer elements within thecapillary lumen, external elements pressed against the wire through anaperture in the capillary, etc. These elements can also serve aselectrical contacts if resistive heating of the wire is implemented.

In some embodiments in which the exact position at which the wire breaksis not critical, wire can be segmented without scoring, with breakageoccurring between the locations where tension is applied to the wire(e.g., where the wire is impinged upon by the two pairs of rollers).

In some embodiments, only a single pair of rollers is required in a wiresegment feeder, and in which there is no risk of the segmented wirecatching on any edges and jamming even if it is distorted, since thebroken end is already within the downstream capillary. Thus such a WSFcan be lightweight, compact, and highly reliable. FIGS. 181(a), 181(b),181(c), 181(d), 181(e), 181(f), 181(g), and 181(h) depict in plan view aWSF in which the downstream capillary is deformable and thus can bepinched by a jaw moved by a suitable actuator so that its inner wall(s)impinge on the wire within and prevent movement. In some embodiments thedownstream capillary may be made using a superelastic alloy such asnickel-titanium or a polymer and is preferably harder than the wire andthus wear-resistant. Or, the capillary may be made from a less elasticmaterial but have very thin walls (the inside surface of the capillarylumen can be continuous, but the outside surface can be machined to thinthe wall). In some embodiments the actuator is a stepper motor-basedlinear actuator with lead screw, a shape memory alloy actuator(producing a high level of force with minimal size and weight), apiezoelectric actuator, or other actuators known to the art.

FIG. 181(a) shows all components of the apparatus with the wire about tobe fed toward the nozzle. In some embodiments a single moving jaw isused, with an optional anvil opposite the jaw to prevent capillarymovement (though other methods may be used), while in other embodimentstwo jaws may impinge on the capillary; these may be driven by a singleactuator (e.g., the jaws may be similar to plier jaws with a singleactuator pulling them together). A center capillary and upstreamcapillary are depicted in the embodiment shown in the figures, separatedby a gap, and with an optional anvil to stabilize the wire within thegap to prevent it from bending while being scored. If the gap is small,however, the anvil may be unnecessary. In some embodiments all threecapillaries shown may be replaced by a single, deformable,multiply-notched capillary: one or more upstream notches are provided toallow access of the roller(s) to the wire, and a notch is provided toallow blade access to the wire.

FIGS. 181(b), 181(c), 181(d), 181(e), 181(f), 181(g), and 181(h) depicta sequence for dispensing a wire segment. In FIG. 181(b), the rollersare rotating, feeding wire downstream. When the control systemdetermines that the currently-dispensed segment is to be terminated andthus the wire is to be severed, the rollers briefly stop as in FIG.181(c), and in some embodiments the jaw, which can be resting againstthe downstream capillary, now presses against it, pinching it tominimize movement of the wire within while the wire is scored. Thescoring blade then scores the wire and retracts as in FIG. 181(d), andthe jaw also retracts. In FIG. 181(e), the rollers are rotating, movingthe wire, now scored, downstream such that the score is within thedownstream capillary. In FIG. 181(f), the jaw has moved towards thewire, pinching it and preventing movement. Once the wire is immobile,the rollers reverse their normal feed direction and apply tension to thewire. The wire then breaks at the score to form a segment and theremainder of the wire upstream of it (FIG. 181(g)). The broken end ofthe remainder of the wire is already within the downstream capillary, sofeeding it forward to repeat the cycle is not a problem: in FIG. 181(h)it has been bed forward so that its downstream end is now positionedwhere the dispensed segment's downstream end had been in FIG. 181(b).

The current-carrying capability of an insulated wire is determined bythe material and cross-sectional area of its conductor, as well as itsability to dissipate heat generated by Joule heating effects. To produceefficient electromagnetic devices such as solenoids, motors, andtransformers, wire—typically copper magnet wire coated with a thininsulator—is normally wound in coils as in the cross-sectional view ofFIG. 182(a). As may be seen, the conductor occupies a large percentageof the coil cross-section, allowing for significant current handling.Coils printed using FEAM may, on the other hand, have considerably lesswire as a percentage of their cross sections (the cross-sectional viewof FIG. 182(b)), which comprise wire and an insulating matrix material,especially if the wire is of small diameter relative to the layerthickness. Moreover, the low thermal conductivity of the thick matrixmakes it more difficult to dissipate unwanted heat.

Several approaches may be used in various embodiments, and either singlyor in various combinations, to maximize the cross-sectional area of wirewithin FEAM-produced interconnects and coils. The first of these is touse multiple small wires—effectively created a stranded vs. a solidwire—that better fills the “racetrack” shape typical of extrudates inFDM-like processes such as FEAM. Other approaches are illustrated (forcoils) in the cross-sectional views of FIGS. 182(c), 182(d), 182(e),182(f), 182(g). In FIG. 182(c), the first approach is to increase wirediameter while maintaining layer thickness, decrease layer thicknesswhile maintaining diameter, or do a combination of both. This approachcan work to the extent that the wires do not short together (e.g.,remain separated by at least some thickness of matrix, given therequired voltage, or are insulated (vs. bare) wires. Staggering thewires from layer to layer (as in FIG. 182(a)) can help reduce the riskof shorting.

As shown in FIG. 182(d), the second approach is to use single ormultiple square or rectangular stands, which better fill the racetrackshape. Single rectangular wires can be bent within the plane of theirwidths (i.e., their larger dimension) using edge bending techniquesknown to the art, and such approaches can be miniaturized. However, insome embodiments it is preferable to use multiple strands which can bendmore easily. Such multiple wires may be fed from individual spools orfrom a common spool, and through multiple capillaries converging ontothe nozzle, or through a single capillary. However, in order to allowfor curved trajectories (as in making coils), individual spools arepreferred since wires on the outside of the turn can be fed (or canpassively be pulled through the capillary) at a higher speed than thoseon the inside of the turn. In some embodiments three independent pairsof drive rollers may be used, while in other embodiments multiplestrands from multiple wire spools can enter the upstream hypotube, andcan be driven while pressed together between the rollers forced togetherby an actuator. At the beginning of a new wire segment when the wire isbeing anchored (or anytime the toolpath is straight, if desired), thestrands can be fed at the same rate. While dispensing wire along acurved path, however, the rollers can separate so that each strand canbe passively pulled independently. In some embodiments each strand canbe independently actively driven. Capillaries for single or multiplerectangular wires may be circular in cross section, or may be of across-section that better controls wire (e.g., prevents it from twistingexcessively). In the case of a common capillary for multiple strands,the capillary may be designed with multiple inlets at its upstream ends,and a common outlet at its downstream end.

In lieu of or in addition to the above approaches in which the wire(s)are made to more closely match the normal extrudate shape, approachesmay be used in some embodiments wherein the extrudate shape is made tomore closely match that of the wire(s). FIGS. 182(e) and 182(f) depicttwo versions of another approach, in which the wire passes through aminiature version of an extrusion crosshead used for wire coating, suchthat wire enters the crosshead nearly horizontally, and the matrixmaterial enters from the top (e.g., fed by a standard filament extruder)and envelops the wire while it passes through a channel in thecrosshead. The resulting coating of matrix can be relatively thin,allowing wires to be placed closer together when forming coils witheither staggered layers (FIG. 182(e) or non-staggered layers (FIG.182(f)).

Another extrudate-shaping approach—explained in conjunction with FIGS.183(a), 183(b), and 183(c) more completely—uses “fences” which controlthe extrudate shape. The result is a coil such as that shown in FIG.182(g), in which the wire (circular here, though square or rectangularmay be used in some embodiments) is surrounded by an extrudate whosenormal side extents have been limited by the fence, minimizing theamount of matrix material and allowing closer packing of wires. Anapplication for such closer packing is in printing circuits with moredensely packed traces (i.e., smaller line and space).

FIGS. 183(a), 183(b), and 183(c) depict 3-D views of a nozzle equippedwith fences to achieve insulated wires such as those shown in FIG.182(g). The use of fences makes the printhead asymmetric (as does thecapillary feeding the wire), so if the printed part does not rotatebeneath the printhead, both the WSF (including capillary) and fenceswould rotate around the nozzle (e.g., keeping the side of the fencetangential to the nozzle motion with respect to the part). As shown inthe close-up image of FIG. 183(a), the nozzle orifice is surrounded onboth sides by fences-elements with surfaces that constrain and mold theextrudate so it cannot extend past the surfaces. The fences shouldpreferably make intimate contact with the underside of the nozzle, sothat little if any extrudate can enter between the fence and nozzle,where it could form a type of molding “flash” (however, if the extrudedmaterial is viscous, then since the pressure in the vicinity of thefences is low, a small gap may be acceptable). The surfaces of thefences can be flat, flat with filleted edges (e.g., vertical edges incontact with matrix material), cylindrical, or have other shapes thatare best determined to produce smooth, controlled extrudate walls. Itshould be noted that such walls need not be flat or vertical (i.e.,perpendicular to the layers), but if they are flat, the sidewallroughness of the printed part, and its transparency (if a transparentmaterial is used) can be improved, especially if the walls are alsovertical.

FIG. 183(b) shows the nozzle and fences from a wider viewpoint, alongwith the wire-feeding capillary, the wire, and the extrudate. The fencesare supported by arms which allow them to independently move out of theway (e.g., upwards, away from the printed layers) when not needed andwhen printing under conditions that may risk collisions, e.g., withmaterial already printed on the layer. In the figure, pivot holes (e.g.,coaxial) may be seen at the tops of the arms to receive pivot pins (notshown) around which arms can rotate, either forward or backward withrespect to the nozzle motion. FIG. 183(c) depicts (from a low angle) anozzle equipped with fences supported by arms, printing a spiral coilfrom outside to inside. For such a geometry, only the left fence isneeded to constrain the extrudate, and indeed, the right fence wouldcollide with already-printed turns of the coil if it overlapped thelayer. Thus the right arm has been pivoted so as to retract it and thefence to a position above the layer. In some embodiments fences mayrotate and/or translate different in order to rise up above the layer.For example, arms supporting fences may pivot around parallel butnon-coaxial axes such that the fences move away from one another in adirection that initially (for small displacements) is perpendicular tothe extrudate long axis/nozzle velocity. Fences are preferably madefrom—or coated with—a material (e.g., a low surface energy material suchas PTFE) to which the extrudate cannot easily adhere. However, fences insome embodiments may be cleaned (e.g., by rubbing across a brush) whenthey are retracted and not in use.

In some embodiments in lieu of rotating fences as shown in FIGS. 183(a),183(b), and 183(c), translating fences may be used. For example,retractable pins with square or circular cross section can be introducedon either side of the orifice through holes formed in the nozzle, andserve as fences. The pins can, for example, extend upwards through thehot end of the printhead, if applicable, and be actuated by shape memoryalloys (e.g., a Ni—Ti wire which shortens, pushing a spring-loaded pinresting against its side downwards), or by fluidic, electromagnetic, orpiezoelectric actuators located at some distance from the nozzle and hotend, and thermally isolated if desired. The pins need not be straight orvertical: for example, a superelastic pin can be delivered through acurved channel. When a fence is to be withdrawn (to allow widerextrudates to be formed, e.g., to speed up printing, or to avoidcollisions with printed material), the pin(s) need merely to beretracted by the actuator(s). If the pins pass through holes that areonly slightly oversize, then withdrawing them can accomplish aself-cleaning action, since matrix material attached to them would bescraped off and remain at the nozzle bottom surface.

In some embodiments, in lieu of movable fences, a single fixed fencebuilt into the nozzle, similar to the guide of FIGS. 143(a), 143(b),143(c), and 143(d) may be used to constrain and shape the moltenmaterial. The nozzle can be actuated so as to rotate such that the fenceis always tangential to the nozzle motion. Since the guide only containsmaterial on one side, it cannot produce extrudates which are narrow onboth sides of the wire. However, for spiral coils, this can beacceptable since the extrudate is constrained on one side by neighboringturns for all but the first turn of the spiral. If the coil windsinwards and then winds outwards without a junction in the wire (e.g.,FIG. 185(e)), then the nozzle can rotate (e.g., 180 degrees) after theinwards spiral is completed and before the outwards spiral is started.

In some embodiments, in order to print coils (or interconnects) with ahigh percentage of metal as a function of total interconnect volume,pre-insulated wire may be used, in which case this may be printed withlittle if any matrix material, without concerns over shorting. While theuse of insulated wire can make forming wire-wire and wire-pad junctionsmore difficult, this is not necessarily the case with solderable magnetwire, which has a coating (e.g., comprising polyurethane) which isremoved in the process of soldering. For example, Soderon® FS/155 MagnetWire (Essex Group, Inc., Fort Wayne, Ind.) is a solderable magnet wiretypical available as a coated copper wire in sizes 7 to 31 AWG. Such awire can be soldered using solder paste and laser soldering methods.

In some embodiments, rather than printing using fibers such as metalwires (e.g., circular, square) which are substantially equiaxed incross-section, printing using flat, ribbon-like fibers may be done. Insuch fibers, the wire thickness (dimension along the Z or layer-stackingdirection) and width (dimension in the planes of the layers) provides alow thickness/width aspect ratio. Use of flat wires can offer certainbenefits such as 1) allowing thinner layers, through the use of thinwires (with widths adequate for the required current); 2) filling ahigher percentage of the cross-sectional area of the printed trace withwire; 3) providing flat pads for attaching components; 4) facilitatingthe printing of large metal areas (e.g., for ground and power planes,capacitors, patch antennas, etc.); 5) providing flat, broad electricalcontacts/pins to facilitate printing connectors (e.g., for a USBdevice).

If the aspect ratio is too low, it can be very difficult to edge bendwire within the plane of the layer, as may be done very easily withcircular or square wire, or example. Thus, in lieu of creating suchbends in order to change the direction of the wire, in some embodimentsthe wire is instead folded at an angle that will provide the desired newdirection. While having the wire lie flat and folding it doesn't lenditself readily to forming wire into arcs and circles, it nonethelessallows very complex wire paths to be printed.

FIGS. 184(a), 184(b), 184(c), and 184(d) depict plan views of flat wire.The wide sides of the wire are designated A and B, while the narrow(i.e., vertical) sides are ignored in this discussion. In FIG. 184(a),the wire follows a straight path, being printed in the direction shownby the arrow, and only side A is up. In FIG. 184(b), however, the wirehas been folded along a 45-degree crease which causes the wiredownstream of the bend to have its side B up and follow a path that isrotated 90 degrees from the original path. In FIG. 184(c), the wire hasbeen folded with a crease having an angle less than 45 degrees from theoriginal path, while in FIG. 184(d) it has been folded with a creasehaving an angle of more than 45 degrees. In general, the angle, gamma,between the wire downstream of the fold and its original direction, willbe twice that of the angle, delta, between the crease and the originaldirection of the wire, as shown in FIG. 184(d).

The wire can be fed through a capillary (e.g., the downstream capillary)having a suitable cross-sectional shape (e.g., rectangular, elliptical)that allows torque to be applied to the wire. To fold and crease thewire, the capillary can be rotated by 180 degrees (flipping side A so itfaces downwards and side B so it faces upwards) while the capillary isre-oriented with respect to the printed part (e.g., by rotating the partor capillary similarly as when performing FEAM with round wire), thusdetermining angles gamma and delta. The wire may be ductile (e.g.,annealed copper) in which case the crease can be flattened at least tosome extent by suitable means, so that the total thickness of the foldequals, or slightly exceeds, twice the wire thickness: minimizing thethickness of the fold can be important such that the fold is thinnerthan the layer surrounding it. Flattening/creasing the fold can beachieved in some embodiments by pressing the upper wire down towards thelower wire using the nozzle, using a tool attached to the printhead(e.g., a blunt probe, a roller), etc. While the wire is being delivered,it can be encapsulated with matrix material, and if the material issufficiently molten, the wire can be folded and creased within it insome embodiments. In other embodiments, matrix material may be depositedon and near the wire intermittently (e.g., just upstream and downstreamof a fold, over a crease) as a means of anchoring the wire; in someembodiment variations this can be followed by depositing matrix material(possibly a lower-temperature material that doesn't remelt the anchoringmaterial) over all or most of the wire to complete the layer.

Because it can be difficult for some matrix materials to flow around awire having a low aspect ratio, in some embodiments the wire isinitially dispensed so that its width is not parallel to the layerplane, but at an angle (e.g., 90 degrees), and after the material flowsaround it, it is re-oriented before the material solidifies. When it isdesirable to print coils, on the other hand, the wire can be printedwith its width vertical, which allows tight, smooth (non-polygonal)spiral shapes to be printed.

With the ability to print with flat wire along complex paths, it becomespossible to produce large, nearly-continuous metal areas from wire, asis depicted in FIGS. 184(e), 184(f), and 184(g). The relative size ofthe structures shown such as the wire width and gap between wires—likeall figures in this specification—are not necessarily to scale.Moreover, although a roughly rectangular region is depicted being formedby wire in the figures, more complex 2-D shapes can be formed.

In the plan view of FIG. 184(e), the wire is printed into a serpentinepattern to define a rectangular region, with two folds (e.g., two90-degree redirections) at the end of each straight run to reverse thedirection of printing. Gaps between the straight runs of wire may beprovided as shown (e.g., to allow matrix material to completely surroundeach run and tack it down) and may be considerably larger than shown. Insome embodiments along the printing direction, the first two folds (toreverse direction) comprise counterclockwise (CCW) twists of the wire,while the next two folds (to reverse direction again) comprise clockwise(CW) twists. This pattern—alternating between pairs of CCW and CWtwists, then repeats as printing continues. As depicted in the plan viewof FIG. 184(f), in other embodiments the pairs of twists can be arrangeddifferently: at the end of the first run there is a CCW twist, but thisis followed by a CW twist in which the wire is tucked underneath thewire immediately downstream of it, rather than overlying it as in FIGS.184(b), 184(c), 184(d), and 184(e). After completing the 180-degreeturn, reversal is accomplished by applying a CW and then a CCW twist. Inthe case of both the pattern of FIG. 184(e) and FIG. 184(f), the twistpattern (alternating pairs of CCW and CW twists such asCCW-CCW-CC-CC-CCW-CCW-CC . . . ) is identical, but the location of thosetwists differs: in one version, each reversal requires two similartwists, while in the other version, the reversal requires two oppositetwists.

To the extent that gaps between runs are objectionable, at least oneother layer of wire (adjacent or several layers away) can be printed inwhich the direction of the straight runs is non-parallel to the firstlayer of wire, thus “plugging” the gaps.

FIG. 184(g) shows in plan view an alternative approach to forming alarge area from wire in which the wire is delivered along a spiral path.In this case, the spiral is rectangular, with four corners/directionchanges per turn, but other shapes are possible (e.g., octagonal spiralswith eight direction changes per turn).

If a wire must change direction multiple times there is potential totorsionally “wind up” the wire between the printed part and the spooldue to the 180-degree twists required each time the wire is folded. Toavoid this, in some embodiments the wire spool is rotated as well as thecapillary and wire, while in some embodiments the twists are not allowedto accumulate by implementing twist reversals as needed. For example, inthe patterns of FIGS. 184(e) and 184(f), the paired CCW and CW twistscancel one another out. However, in the spiral pattern of FIG. 184(g),in which the wire always turns in the same direction, the wire twistsCCW at each time, as seen from the capillary as shown. In such a case, arotating spool can be used. Or, CW and CCW twists can both be used(e.g., approximately equal numbers) to avoid torsion accumulation, suchas in the plan view of FIG. 184(h).

It can be challenging to fully encapsulate flat wire—as compared withmore equiaxed wire—with matrix material when the only source of thematerial is above (i.e., on one side of) the wire (e.g., an extrudernozzle). In some embodiments, in addition to a nozzle deliveringmaterial from above the wire, a channel may be used below the downstreamcapillary, and for example, running alongside it in parallel, tointroduce material below the wire as well. The flow of material underthe wire can also minimize any tendency for the wire (whether flat orequiaxed) to be pushed downwards by the flow of material from above,helping it remain more centered vertically. The channel (e.g., a metaltube) moves (e.g., rotates) along with the capillary as needed. In someembodiments, fences such as those in FIGS. 183(a), 183(b), and 183(c)can incorporate apertures on their surfaces intended to introduce matrixmaterial along the side and/or underneath the wire. In some embodiments,rather than a single central orifice, the nozzle can include two or moreorifices arranged along a line that is perpendicular to the wire axis(i.e., straddling the wire); matrix material issuing from these orificescan more easily go around the wire, whether flat or equiaxed.

In some embodiments, especially those using flat wire and/or fences,stranded, perforated, or Litz wire can be used instead of solid (i.e.,monofilament) wire so that matrix material need not be forced to flowaround a large single wire, but can flow around smaller strands orthrough perforations. In some embodiments the flow through the nozzlecan be pulsed instead of continuous, to aid in uniform encapsulation ofthe wire; this can be achieved for example using a small oscillatingpiston in a cylinder formed in the hot end (or nozzle).

If flat wire is desirable, wire need not be flat to begin with, but canbe flattened by crushing as needed, and in the regions it is needed.Thus, for example, wire can be round in cross-section when followingcurved trajectories, but when a flat region is needed for a patchantenna or capacitor or connector contact, it can be flattened over aspecified length. Flattening can be accomplished with ductile wire suchas copper (or tin-coated copper) using pressure from rollers that areused in the WSF, such as the downstream rollers of FIGS. 180(a), 180(b),180(c), 180(d), 180(e), 180(f), and 180(g). The drive and/or idlerroller can be forced against the opposite roller by a suitable actuator(e.g., pneumatic, hydraulic, motor-driven lead screw), flattening thewire (i.e. decreasing thickness, increasing width, and producing a flattop and bottom). If the rollers are oriented as shown (axes vertical)then the wide dimension of the wire will initially be vertical, but thewire can be twisted if needed by approximately 90 degrees so that thewire lays flat. Or, in some embodiments the rollers are oriented atother angles (e.g., with their axes horizontal).

Flat wire is generally best delivered using a WSF in which at least thedownstream capillary is shaped so as to prevent twisting (e.g.,rectangular, elliptical, or racetrack-shaped). If the WSF can deliverboth flat and round wire (e.g., wire that is flattened from round toflat by the WSF rollers, or simply wire that is sometimes round andsometimes flat, depending on what is loaded into the WSF), thencapillaries can be shaped so as to accommodate either one. In someembodiments the cross-section of the capillary lumen may be shapedaccording to the Boolean union of a circle and a rectangle that overlapsit on center or off-center (e.g., forming a keyhole shape), thusallowing the capillary to accommodate both wire shapes, while preventingtwisting of flat wire.

Rotary and linear motors, both stepper motors and motors for continuousrotation (e.g., brushless DC motors, synchronous motors) can be producedusing FEAM technology. These may incorporate permanent magneticmaterials which are inserted (e.g., sintered magnets inserted into adevice during or after fabrication) or which are printed (e.g., NdFeB,SmCo, or ferrite powder mixed with a binder and printed using FDM-likemethods). Variable reluctance (VR) devices may also be produced, inwhich only soft magnetic materials such as iron, steel, cobalt, nickel,alloys (e.g., nickel-iron) are used. These materials may be incorporatedinto devices as solid objects (e.g., blocks, foils, wire), may be builtup by depositing soft magnetic composite (SMC) materials, may be builtup using cold spray and capillary cold spray methods, ultrasonicwelding, etc.

FIGS. 185(a), 185(b), 185(c), and 185(d) depict in 3-D views anexemplary design for an axial flux, VR rotary stepper motor having sixstator poles and eight rotor poles. In the design shown, three statorpoles would suffice to produce rotation, however, six poles are used toincrease torque. The design shown has a step size of 15 degrees, but canbe microstepped with appropriate drive electronics. Other combinationsof stator and rotor pole pieces are possible, such as eight stator polesand six rotor poles. While the motor shown is considered an “inboard”motor (with an internal rotor), similar motors that are “outboard” (withexternal rotors) can also be designed; such motors may be preferable foruse in unmanned aerial vehicles, for example. Similar designs can beused for motors providing continuous rotation such as switchedreluctance motors. For such motors, sensing of rotor position can beprovided, if required, by incorporating holes or other features in theprinted rotor, and incorporating sensors (e.g., Hall effect,photosensitive) in the stator or related components, for example.However, sensorless (e.g., DSP-based) techniques for driving the coilscan also be used.

FIGS. 185(b) and 185(d) are cross-sectional 3-D views. The motorcomprises a rotor with multiple pole pieces incorporated, a shaft fixedto the rotor, a base, a top, multiple stator poles, and multiple coils.The main body of the rotor may be fabricated from a non-magnetic,possibly dielectric material such as a thermoplastic, with cavities toreceive the rotor poles. The rotor and stator poles may be fabricatedfrom ferromagnetic material: for example, an SMC may be deposited into acavity, or directly printed (e.g., by extrusion). While aspects of themotor shown in FIGS. 185(a), 185(b), 185(c), 185(d), and 185(e) aresimilar to some “salient pole” motors, since the rotor is composed ofnon-magnetic material, there is no need for the poles to protrude, andthey can be flush with the rotor if desired. The shaft may be composedof any desired material, such as a polymer, composite, or metal that isprinted, a solid object (e.g., a steel rod) that is inserted, etc. Inthe design shown, the shaft is designed to rest due to its weightagainst a smooth surface on which the motor is placed, forming a bearingand allowing the upper and lower gaps between the rotor and stator polesto be maintained. The bottom of the shaft is tapered to reduce frictionwith that surface. In some embodiments other types bearings may be used,including bearings which involve placing plastic, ceramic, or metalballs into the motor during printing or afterwards. An advantage toinserting balls—in addition to replacing sliding friction with rollingfriction—is that the balls can fill clearances between parts fabricatedmonolithically without assembly. When it is desirable to use a sleevevs. a ball bearing, however, and the bearing is to be fabricatedmonolithically, excessive shaft/bore clearance may be an issue. In someembodiments the shaft is designed with compliant elements that allow itto be expanded in outside diameter by the insertion of an object (e.g.,a ball) during or after fabrication, thus reducing the clearance(similarly, the inside diameter of the bore could be reduced). A bushinghandling both radial and thrust loads can be made using a shaft with anapproximately spherical section that is expanded into a bore of similarshape. Approaches based on inserting objects, releasing built-instresses, building in moveable elements that can be retained in newpositions (e.g., by local melting, by ratchets) can in general be usedto reduce clearances between moving elements.

The base and top include holes to accept the shaft, thus serving asradial bushings, and the stator poles are fixed between them.Surrounding each rotor pole is a coil such as a multi-layer, multi-turncoil. FIG. 185(c) depicts the motor as-fabricated, with support material(e.g., soluble support such as PVA) in locations where required tosupport the structure. FIG. 185(d) depicts the coil and stator poles inmore detail, and the closed-loop path of magnetic flux (shownapproximately and shown flowing clockwise, but which may actually flowcounterclockwise) flowing through the upper horizontal portion of astator pole, the upper air gap between stator and rotor poles, the rotorpole, the lower gap, the lower horizontal portion of the stator pole,and finally, closing the loop through the vertical portion of thestation pole. The overall flux path is short, reducing iron losses inthe motor. When the coils are energized and no rotor poles are alignedwith the energized stator poles, the nearest poles will be attracted tothe stator poles so as to minimize the reluctance of the motor, thuscausing the rotor to rotate through an angle. By turning on current togroups of stator poles in the proper sequence as is known to the art,rotation may be continued, allowing for 360-degree motor operation.

Lastly, FIG. 185(e) depicts a 3-D view of a coil that can be printedwith FEAM for use in the motor or other devices. The coil comprisesspiral turns on multiple layers: for clarity, only about three turns areshown, and only about two layers are shown in the figure. Since it isdesirable in some embodiments to minimize the number of junctions, coilswith many layers can be built from sub-units, each comprising two spiralcoils as shown in FIG. 185(e), which can be printed using a single wiresegment. The spirals on each layer are connected to one another throughtransitions which extend vertically or diagonally to bridge layers.Transitions may be made of wire (i.e., the wire need not be broken/cut,but can simply be redirected into another layer) or if two wires areinvolved, can comprise any conducting material (solder, ECPC, etc.). Thespiral turns on even and odd layers alternate, such that current flowsalways in consistent direction. In the example shown, current flowsinwards (or outwards) on lead 1 on layer 1, spirals clockwise inwards,then transitions to layer two, continuing to flow clockwise but nowspiraling outwards, and ultimately exits the coil on lead 2. A coil withmore than two layers would have a transition between layer 2 and layer 3near the outer part of the spiral, in lieu of lead 2, since sometransitions must be near the center of the spiral (e.g., continuouswire) and some (e.g., solder) near the periphery. Other coil windingsare possible, including ones in which all external ends of the spiralsare connected together in parallel and to one lead, while all internalends of the spirals are connected together in parallel and to anotherlead. If a coil such as that of FIG. 185(e) is produced from a singlewire segment, then the thickness of each layer of the coil is preferablyhalf that of the thickness of layers in the surrounding device, and theorder of fabrication for the two layers X and X+1 which include the coilis: 1) print everything on layer X other than the coil; 2) print thedouble-spiral coil, starting on layer X and ending on layer X+1 (note:multiple coils can be printed at this time); 3) print everything onlayer X+1 other than the coil.

FIG. 186(a) is a 3-D view of a method of fabricating a stator polehaving a design similar to that of FIGS. 185(a), 185(b), 185(c), 185(d),and 185(e), while FIG. 186(b) is a cross-sectional elevation view of afabricated stator pole. In the method illustrated, soft magneticmaterial is provided in the form of blocks (e.g., rectangular prisms asshown, but potentially other shapes (e.g., other space-filling shapessuch as hexagonal prisms) may be used, as well as non space-fillingshapes such as cylinders of equal diameter. Blocks may be inserted intoa housing (e.g., with thin walls) that is 3-D printed to accommodatethem, and insertion may occur during fabrication or afterwards(backfilling of such a housing with SMC is another method to createpoles). For example, the blocks in FIG. 186(b) could be inserted afterprinting the housing, with blocks in the lower half inserted from thebottom, and blocks in the upper half inserted from the top. Or, ifblocks must all be inserted from the top, then insertion of lower blocksmust occur during fabrication by pausing printing at one or morelocations where insertion of a block would not interfere with furtherprinting (i.e., the cavity is deep enough), inserting one or moreblocks, and then continuing.

Since at least small gaps between blocks are inevitable, and since suchgaps have high magnetic reluctance, it is desirable to minimize thenumber of gaps along the flux path. For rectangular prism-shaped blocks,an arrangement that accomplishes that for a stator pole is shown inFIGS. 186(a) and 186(b), in which blocks are inserted with their longdimensions both horizontal and vertical, since the flux path is a closedloop. Blocks are not necessarily of the same length, though if of thesame length, it may be easier to maintain an adequate supply in theprinter, and dispensing may be simpler. Since the flux through rotorpoles is vertical, such a pole would best be constructed solely fromblocks with their long axes vertical. Blocks may be coated with anadhesive (e.g., a pressure sensitive adhesive, possibly covered with astrip that is peeled off as they're dispensed) to retain them, or ifinserted into a cavity, the cavity may contain an adhesive (e.g. a lowviscosity slowly-hardening one, allowing it to seep into the void spacebetween blocks), or they may be held in place by friction and/or thematerial deposited around and over them to encapsulate them, which insome cases may be deposited between layers or groups of blocks. If amaterial fills gaps between blocks, it may in some embodiments containmagnetic particles (e.g., the material can be an SMC or ferrofluid) tominimize reluctance.

Blocks may be inserted by a variety of manual and automated pick andplace methods, including using pick-ups that are magnetic, or whichincorporate vacuum or an adhesive, etc. Blocks may be dispensed from acartridge directly into printed cavities, or dispensed and fed topick-ups. FIGS. 187(a), 187(b), 187(c), 187(d), 187(e), 187(f), 187(g),and 187(h) depict in plan view a cartridge comprising a housing and twoplungers—narrow and wide—used in some embodiments to dispense blocks (inthis case, in the form of rectangular prisms), e.g., to manufacture amagnetic pole (however, blocks of various shapes may be used for anumber of other purposes, such as serving as drive shafts, reinforcingelements, vertical/interlayer vias, magnets (if made from a permanentmagnet material), etc.). In FIG. 187(a), the housing is empty. A holethrough which blocks can be ejected (e.g., downwards, perpendicular tothe plane of the figure) by pushing, pulling, or simply falling out, isshown in one corner of the interior volume. The housing may be designedwith such dimensions, or from such materials (e.g., with elastomericsurfaces) that blocks do not move readily without being pushed by aplunger.

In the plan view of FIG. 187(b), the housing has been filled with blocksforming numbered columns (e.g., 1, 2) and lettered rows (e.g., A, B) andthe block over the hole has already been ejected (e.g., by a pin beinglowered to force it out), where for example it may enter a magnetic polehousing as in FIG. 186. FIGS. 187(c), 187(d), 187(e), 187(f), 187(g),and 187(h) depict in plan view a sequence for ejecting additionalblocks. In FIG. 187(c), a narrow plunger has pushed forward all theblocks in column 1. Once a block is over the hole, it can be ejected, asmay be seen in FIG. 187(d). In FIG. 187(e), the narrow plunger hasadvanced again, pushing the blocks in column 1 forward, and in FIG.187(f), all the blocks in column 1 have been pushed over the hole, oneat a time, and been ejected. At this point, the narrow plunger retractsas in FIG. 187(g). Next, the wide plunger advances, pushing the blocksin column 2 into the location formerly occupied by column 1 blocks. Thecycle shown in FIGS. 187(c), 187(d), 187(e), 187(f), 187(g), and 187(h)can then repeat until as many blocks as are needed are ejected. The wideplunger may in some embodiments be spring-loaded rather than activelydriven, since it cannot advance until all blocks in a given column havebeen ejected and the narrow plunger has withdrawn as in FIG. 187(g).

Other ways of providing and dispensing blocks may be used in someembodiments. For example, blocks may be attached to a continuous tape,or be retained within compartments attached to a continuous tape(similar to electronic components fed to pick and place machines).Blocks may also be pushed out of a tube that is at an angle with respectto vertical, so that blocks falling out of the tube rotate into adesired horizontal position.

FIG. 188 depicts a “3-D printed hybrid electronic module”, or 3DPHEM: adevice in which the mechanical structure and interconnects are printedusing FEAM from a dielectric matrix material and metal wire,respectively, and components such as electronic components, MEMS, andoptoelectronic components (packaged or bare die) are inserted during orafter printing. 3DPHEMs are similar in some respects to circuit cardassemblies (populated PCBs) but can have a very wide range of 3-D shapes(not merely rectangular and flat), can be lightweight (e.g., by printingwith pockets or widely-spaced infill), compact (3-D structured withcomponents distributed throughout the volume, and potentially hundredsof layers), robust (with encapsulated, protected components), and can berapidly manufactured by an integrated, automated process in a singlemachine. Junctions between wires—and between wires and the pads ofinserted components—in a 3DPHEM may be made by various approachdiscussed above including soldering (e.g., laser soldering), welding(e.g., laser welding), electrically conductive adhesives, and ECPC, aswell as wire bonding (e.g., thermosonic wire bonding), the latter beingespecially attractive for bonding wire to the pads of bare die.

To fabricate a 3DPHEM, dielectric matrix material (which may be chosenfor favorable properties such as high glass transition temperature, lowdielectric constant, stiffness, etc.) is printed layer by layer,including one or more cavities into which components can be placed. Oncea sufficiently deep cavity has been created to house a given component(packaged or bare die) such that it won't protrude), the component(e.g., a surface mount component) can be placed in the cavity with itspads (or leads, such as a gull-wing lead) facing upwards, using standardpick and place techniques as adapted to a 3-D printer (e.g., a vacuumpickup attached to the printhead). Next, wire encapsulated in matrixmaterial can be printed together using FEAM according to the circuittopology such that the bare ends of wires needed on the current layeroverlap pads on the component. Next, a junction is formed between thecomponent pads and the wires. In some embodiments this is done usingsolder paste applied to the wire and pad after the wire is printed, orbefore the wire is printed: the paste can be reflowed (e.g., by lasersoldering) as fabrication progresses, or if the solder reflowtemperature is low relative to the matrix material and maximum componenttemperature; reflow can be performed after all layers of the 3DPHEM areprinted. In other embodiments the junctions is formed by depositingsmall quantities of ECPC over the wire and pad, or onto the pad beforethe wire is printed, or by laser welding or thermosonic bonding, etc.Junctions between wires which may be needed in the current layer arealso created. Before proceeding to the next layer, the remaining matrixmaterial required for the layer (which may include material forming a“roof” over the inserted component) is deposited. This process repeatsuntil all layers are formed, all components are inserted and joined, andall wire-wire junctions are made. If any support material has been used,it can then be removed. In some 3DPHEMs, it is desirable to efficientlyremove heat from a component; metal wires can be used for this purpose,but also, cavities may be produced within the matrix material allowingaccess to the component surface by cooling fluids (e.g., leak-proof,sealed channels can be formed around a component), or allowing insertionof a cooling element such as a heat pipe or heat spreader that makescontact with a component embedded deep within the 3DPHEM. Heat can alsobe removed by use of a matrix (from which the entire 3DPHEM is made, orjust a portion) with high thermal conductivity, such as a polymercontaining cubic boron nitride powder, or even metal powder below thepercolation threshold.

A what-you-see-is-what-you-get design/fabrication process may beimplemented in some embodiments, in which the design engineer canspecify and visualize the exact size and positioning of components,wires, and junction cavities in CAD, just as it will be in the actual3DPHEM. An exemplary process flow is as follows (assuming, for ease ofexplanation, 3-D CAD terminology used by SOLIDWORKS (Dassault SystémesSolidWorks Corporation, Waltham, Mass.)), which is compatible withstandard mechanical 3-D CAD software and the standard .STL files used in3-D printing:

Step 1: CAD design. a) Create a circuit schematic and bill of materials,and download or create CAD models of all the components to be insertedinto the 3DPHEM. If desired, add margins around each component to allowfor manufacturing tolerances, ensuring all components will fit intotheir respective cavities. The margin can take into account the desireto have good thermal contact between the component and the cavity walls,ceiling, or floor, or the desire to decouple stress in the structurefrom the device, allowing it to “float” within the cavity, suspended bythe wires joined to its pads. Give each component file a suitable name(e.g., Cap1.sldprt for a particular capacitor). b) Create the 3-D shapeof the dielectric portion of the 3DPHEM in CAD (this may be modifiedduring subsequent steps). Add other features if desired such as channelsfor flow-through cooling using air or (especially if all electricalcontacts will be fully encapsulated) liquid. Give the part a name suchas Dielectric.sldprt. c) Create a 3DPHEM assembly file (e.g.,3DPHEM.sldasm) and insert the Dielectric.sldprt file. d) Insert all thecomponent part files in the assembly and constrain using mates. e) Whileworking in the assembly, create a part file (e.g., Wiring.sldprt) withthe geometry of the wires needed to connect the components to oneanother (e.g., FIG. 189(a)), and mate the wires to the component pads.Individual wires will often have the same cross-sectional shape, and canbe created using the extruded boss/base feature (standard or thin),sweep feature, etc. To specify whether a portion of a wire is to beinsulated (i.e., coated with dielectric) or bare, adjust the width ofthe wire shape in CAD (e.g., wide to designate insulated portions,narrow to designate bare portions, FIG. 189(b)); the width will later beextracted and used to control polymer flow from the nozzle. Typicallythe wire ends will be bare, and will overlap pads on the components orwill be bare so as to create a wire-wire junction: intra-layer (e.g.,between two wires end-to-end or arranged in a “T” or “Y” junction, orthree wires meeting end-to-end), inter-layer, or both (wires, includinglong wires with a serpentine or spiral shape, may be joined to acomponent pad merely to help dissipate heat). f) While working in theassembly, create one or more part files (e.g., Junctions.sldprt)containing the 3-D shapes of rectangular boxes which define the volumesand locations of junctions. Position the boxes using mates so that theyoverlap groups of wires to be joined with wire-wire junctions (intra-and/or inter-layer), or overlap wires and pads to be joined withwire-pad junctions (FIG. 189(c)). Different files might be created fordifferent types of junctions such as intra-layer junctions, inter-layerjunctions, and wire-pad junctions, since the machine parameters requiredto form these junctions may differ. The box size might be variedaccording to the needs of the junction, encoding the amount of solderpaste required, laser power or time required, etc. g) While workingwithin the assembly, edit the Dielectric. sldprt file and use the cavityfeature to select the files (Wiring. sldprt, Junctions. sldprt, and eachcomponent file) to be subtracted and produce voids in theDielectric.sldprt file. Add the cavity feature, resulting in a geometryin which the volumes occupied by the components, wiring, and junctionsare missing. h) Export the Dielectric.stl file from Dielectric.sldprt;export the Wiring.stl file from Wiring.sldprt; export the Junctions.stlfile from Junctions.sldprt.

Step 2: File processing. By interpreting each .stl file differently, aFEAM 3-D printer can be directed to process the three materials ofinterest (dielectric, metal wire, and junction material (assumed here tobe solder paste which will be laser soldered) even though the .stl filesthemselves contain no material information. i) Process Dielectric.stl asusual (e.g., using slicing software such as Slic3r) to generate standardG-code (e.g., Dielectric.x3g) which controls nozzle motion. j) Usingspecialized software, process Wiring.stl to generate a custom G-codeASCII file (e.g., Wiring.feam) that controls wire deposition (includingnozzle X/Y position, feeding and segmenting). The software is able toslice the file, extract contours, calculate a set of vectors whichfollow the wire trajectory (as in FIGS. 178(a), 178(b), 178(c), 178(d),and 178(e)), and insert codes which turn on and off the polymer flowbased on the local contour width to allow insulated and bare regions ofwire to be formed. k) Using the software, process Junctions.stl (one ormultiple files) to generate a custom G-code ASCII file (e.g.,Junctions.feam) that controls the positioning and activation (e.g., onand off timing) of the solder paste dispenser and the laser, and mayalso control laser power during pre-heat and soldering, or otherparameters according to junction type and the specific junction geometry(e.g., number of wires being joined). The centroid of the box can becalculated to determine (with an offset) the position of the solderpaste dispensing needle tip, while the calculated box volume candetermine the solder volume to be dispensed (e.g., the time ofdispensing, which may be different for different components anddifferent junction types, etc.)

Step 3: Consolidation and printing. 1) Import all three G-code filesinto specialized printer control software and consolidate them into asingle machine control file which includes all relevant machine controlcommands. m) Print the 3DPHEM using the custom software: insertcomponents manually or using automated pick and place approaches asneeded.

In some embodiments the electrical contact between a component pad and awire (e.g., in a 3DPHEM) is based on preloading the component so thatits pads contact wires or conductive materials making contact with thewire (e.g., a compliant blob of ECPC). For example, a component may beinserted with its pads facing downwards to contact wires below (e.g., ina cavity). While pressure is applied to the component to preload it,material can be extruded above the component to lock it in place,maintaining the preload.

3DPHEMs and other structures in which components are inserted may needto be reworked involving replacement of a component. If the component isplaced within a cavity in which at least one surface (e.g., the floor)is removable, it the surface can be removed and the component replacedonce its electrical contacts to the wires have been loosened. In thecase of components merely preloaded against wires or conductivematerials, the component need only be extracted since its pads are notbonded to anything.

For applications (e.g., power and ground planes, capacitors, patchantennas) in which it is desirable to integrate into the device acontinuous or near-continuous sheet of metal, this can be approximatedusing various techniques. The use of flat wire has already been noted.Depositing parallel lengths of wire on multiple (e.g., adjacent) layers,in which the lengths are staggered between layers (like bricks in awall) can be done in some embodiments, such that the wire in one layercovers the gaps in another. Arranging parallel wires in a layer so theyare oriented at a non-zero angle (e.g., 90 degrees) with respect to wirein another layer can also be done in some embodiments. In someembodiments, “hatched” or “mesh” power and ground planes can be used,which are porous and easily achieved with wire laid in patterns such asserpentines/zigzags and spirals.

An inserted part such as an electronic component may have its pads in adifferent position than anticipated when designing the routing of wiresin CAD. To compensate for this, in some embodiments a vision system maybe used to determine the precise location and orientation of acomponent's pads, and adjust the path along which wire is laid—as wellas the location of solder paste dispensing and laser spot position, ifapplicable—so as to compensate for the error in pad location andorientation and ensure that wires are properly located with respect topads to allow reliable junctions to be formed. In some embodiments afterthe component is inserted, an adhesive, underfill, etc. is used toensure that once the component is placed and inspected/measured, it willnot move (e.g., due to vibration, acceleration, forces applied whiledepositing solder paste, etc.). In some embodiments material (e.g.,matrix material) is deposited on top of and/or on the sides of thecomponent to fix it to the surrounding structure.

Sacrificial fibers incorporated into structures, once removed (e.g., bydissolution) can form channels for fluids that are much narrower thancan easily be produced directly. Such channels can also be used toaccommodate solid objects, e.g., an optical fiber, through which lightcan travel within the structure (e.g., to stimulate or probe amicrofluidic volume within) without being affected by the opticalproperties of the structure. A similar result can be obtained throughthe encapsulating using FEAM of hollow fibers. In some embodimentschannels produced in structures by any method can be filled during orafter fabrication by conductive fluids such as ionicsolutions/electrolytes, low melting point alloys (e.g., gallium-indium),and solders.

3DPHEMs, circuits, and other devices fabricated according to someembodiments can contain components—either inserted or fabricatedin-situ—that need to be modified for use. For example, an insertedEEPROM or FPGA device may need programming, an inserted battery may needcharging, an inserted or fabricated component may need laser trimming toits correct value. In some embodiments these modifications can beperformed as the device is fabricated, rather that afterwards or, in thecase of inserted components, beforehand. For components that may befabricated in-situ such as resistors, the characteristics (e.g.,resistance) may be measured during or shortly after the component ismade, such that the component can be adjusted to the correct value. Forexample, the length and/or path of a resistive wire used as a resistivecomponent can be adjusted in real time as the wire is deposited, basedon real-time measurements of resistance.

ECPCs (and SMCs) can in some embodiments be formulated using waxes andhot melt adhesives as the polymer or portion thereof. Such adhesives mayhave improved adhesion to substrates such as metals (e.g., wire,electronic component pads) when compared to polymers such as TPEs.Moreover, they may have a much lower viscosity, facilitating mixing withconductive (or magnetic) powders, and dispensing. An example of a hotmelt adhesive suitable for use is Tecbond 7718, a low viscositypolyamide hot melt adhesive (Ellsworth Adhesives, Germantown, Wis.).

When printing structures from soft materials, material may deform toomuch under gravitational forces, inertial forces (e.g., if the structureis on a moving platform), tension applied by the moving nozzle throughthe solidifying extrudate, tension applied by the wire anchored in thestructure, and shrinkage of the solidifying, cooling material (ifthermoplastic), which cannot be resisted by other such material due tothe low modulus. Thus in some embodiments such structures are builtalong with a relatively rigid support material which stabilizes itduring fabrication. The support material may be removed by peeling off,breaking off (if friable), melting, or dissolution. A suitable rigidsupport material for TPE such as Kraton D1161P and StarClear® 1003-0000(Star Thermoplastic Alloys & Rubbers, Broadview, Ill.) is polyvinylalcohol (PVA), which is preferably kept in a dry box and fed through atube to protect it from humidity.

In some situations, the orientation required for actuation of anactuator or displacement of a sensor may not (e.g., in a robot) be thesame as the optimal orientation for fabricating the device. In suchsituations in some embodiments the device can be fabricated in theoptimal orientation, but a fluid coupling may be created between thedevice and the desired actuation or displacement. For example, asolenoid actuator is best printed with its axis of actuation vertical(perpendicular to the layers). If the required actuation is horizontal,then the solenoid plunger can deform a diaphragm or bellows or translatea piston in a cylinder, pressurizing a liquid. The liquid pressure canthen be communicated to another diaphragm, bellows, or piston having anaxis of actuation that is horizontal; the conduit between the two setsof bellows, etc. may easily be fabricated with a right-angle turn orequivalent.

In some embodiments, actuators or sensors may be fabricated whichinclude a ferrofluid that is applied during fabrication or afterwards.Ferrofluids are able to sustain magnetic fields with low reluctancecompared to air, and yet cannot sustain mechanical stress. Thus anactuator such as the dome actuator of FIGS. 26(a) and 26(b) might haveferrofluid between neighboring turns of wire, to better couple themagnetic field from one turn to the other. A variety of compliantelectromagnetic actuators may be produced which combine an elastomericstructure with hollow regions that are filled with a ferrofluid and/orferromagnetic particles, and a coil is provided to generate a magneticfield. When the field is turned on, motions of the fluid will force thestructure into a new shape, or in the case of particles, they maytransition from an unjammed/flowable to a jammed state or vice-versa,providing variable stiffness and/or actuation.

In some embodiments, the wire should be heated to allow better controlover vertical centering within the extrudate. This can be accomplishedby heating the capillary, by Joule heating of the wire, by inductiveheating of wire or capillary, etc. One method of heating the capillaryis wrapping it with (if the capillary is metal, insulated) heating wire(e.g., Ni—Cr).

In some embodiments, structures made with embedded wires can be made toself-heal after a fissure, tear, or other rupture, by using Jouleheating of the wires to soften the surrounding material (ifthermoplastic), release a micro/nano-encapsulated adhesive materialwithin the surrounding material, etc.

Ramifications:

In some embodiments, wire can be included within extrudates of polymeror other material as a matter of course, throughout the fabricatedobject, rather than be stopped (e.g., cut) and started so as to includeit only where needed. In such embodiments, if an object is built inlayers, vs. in a continuous, quasi-helical fashion, wire may still bestopped and started between layers. In such embodiments, the wiresremain electrically isolated from one another except where they passthrough regions of ECPC that themselves, or through other regions ofECPC, form an electrical junction between the wires. As noted above,polymer filament may be supplied with wire pre-embedded, and the entirevolume of the filament need not necessarily be softened to allowdeposition of extrudates and fusing to previously-deposited extrudateson the same or the previous layer: melting the outer surface of thefilament can be sufficient.

In general, conductors can be wire, ECPC, or a combination of the two.In some embodiments, rather than limit ECPC to junctions between wiresas in FIGS. 8(a) and 8(b), ECPC can be provided throughout the entirelength of wire-containing extrudate. This minimizes the transitionsbetween pure, dielectric polymer and ECPC that are required, and allowsthe conductivity of the ECPC to contribute to the overall conductivityof the extrudate. However, neighboring extrudates which are not intendedto be shorted along their common boundary may not both have ECPCthroughout their volumes; thus conductive, wire/ECPC containingextrudates will generally need to be spaced further apart thanconductive wire-only extrudates. Also, ECPC is generally stiffer thanpure polymer, thus altering (for better or worse) mechanical propertiesof the fabricated object, and is generally more costly.

Components made with the processes disclosed herein may be combined toform larger components, including those too large to fabricate in asingle machine, with electrical junctions made between multiplecomponents so that current can flow across the boundaries. For example,two components may be fabricated with exposed regions of ECPC at thesurfaces that will be joined together, with such regions serving asconnectors. In some embodiments, providing pressure at the opposingregions of ECPC is sufficient to create a satisfactory junction, whilein other embodiments the ECPC may be softened (e.g., if thermoplastic)or coated with a conductive adhesive or other intermediary. In someembodiments, wire may protrude from one component and be pushed intoECPC in another component.

In some embodiments in which the printhead moves in at least one axisparallel to the layers, fabrication may be accelerated and accuracyimproved by independently positioning the nozzle and possibly,closely-associated components, with respect to the move massiveprinthead. For example, when rounding a sharp corner, the printhead mayfollow a path with a larger radius than is required by the extrudate,while the nozzle, independently actuated to move over small distanceswithin the printhead, follows the desired contour far more exactly. Suchpartitioning between small, rapid motions and large, slower ones can beapplied to FDM and similar processes in general.

Regions of wires intended to be bare (e.g., for connection to externalcircuitry, or for the insertion of external components into afabrication object, or for applications requiring freely-moving wire)can be nonetheless anchored temporarily, as an aid to wire delivery, insacrificial support material. After this is removed, the bare wireremains exposed.

Insulated wire (e.g., magnet wire with thin insulation) may be used inlieu of bare wire, e.g., to obtain coils with more tightly-spaced turns,by stripping the insulation off the ends of the wire as needed. This maybe done using heat, mechanical scraping or abrasion, laser, chemicals,ultrasonic energy, etc.

Abrupt transitions in elastic modulus between polymer matrix and ECPCmay lead to stress concentrations; these can be mitigated by creatinggradients in powder filler concentration, such that only regions abovethe percolation threshold are nonetheless conductive, by altering thegeometry, or by incorporating other materials or grades of materialsthat can help produce a more graduate transition. In some embodiments,polymers can generally be filled with powder and thus have fairlyuniform elastic modulus: some of the powder is conductive (e.g., forjunctions) and some is not.

The quality of junctions produced using FEAM can be determined as theobject is fabricated using in-situ inspection. For example, theresistance between two region of ECPC on the same layer may be measuredby extending probes into both of them, or by making contact with wirethat is embedded within them (e.g., as the wire is delivered andembedded). To measure the resistance between two regions on two adjacentlayers N and N+1, the region on layer N can be designed to be onlypartially overlapped by the region on layer N+1, such that a probe canextend into the non-overlapped portion while another probe is insertedinto the region on layer N. Junctions which fail the inspection criteriafor resistance and which are needed for functionality may be in someembodiments reworked (e.g., re-melted, or melted together by a jet ofhot air, or material can be melted, extracted by vacuum, andredeposited), or in some embodiments simply bypassed by formingadditional junctions elsewhere.

In some embodiments, filament may be deposited before polymer isdeposited, not simultaneously or subsequently, and a mixture of theseapproaches may be used throughout a single fabricated object. Forexample, filament may be placed onto the top of an existing layer,optionally tacked down at certain locations with polymer, and materialextruded over it more or less as in conventional FDM. In this scenario,the filament will tend to be at the bottom of the new layer, notcentered vertically within it. Thus in some embodiment variations, apartial layer of thickness less than the desired layer (e.g., half thethickness) can be deposited, followed by filament, followed by anotherpartial layer. Or, the filament can be spaced vertically by deployingonto it small “beads” which support it, or if ductile it can be bent(e.g. by the head of FIG. 36) to form small supporting regions whichsuspend the majority of the filament above the surface.

Rather than form separate regions of ECPC as in FIG. 8(b) to create ajunction on a layer such as layer N, in some embodiments the regions canbe combined into a single ECPC region, with ECPC deposited to fill inthe entire region, for example, depositing ECPC into a trench left afterforming the pure polymer extrudates with embedded wire. In someembodiments the same is approach is used for junctions that span two ormore layers, e.g., with a multi-layer trench backfilled using ECPC. Insome embodiments, regions of ECPC may be shaped to provide both anintra-layer junction such as FIG. 8(a) and an inter-layer junction suchas FIG. 8(b).

In some embodiments, objects can be fabricated entirely in aunidirectional raster deposition mode (with a fast and slow axis), suchthat the orientation of asymmetric nozzles, external capillaries, andthe like need not vary during deposition as when depositing curvedextrudates in a vector deposition mode. Thus no rotation of printheadcomponents or of the fabricated object (as in FIG. 42) is required. Insuch a mode, the layer cross sectional area is formed by a set ofparallel extrudates—e.g., some with and some without filament—alldeposited by the printhead moving in one direction (e.g., along positiveX). Assuming printhead rapid motion along X (the “fast axis”), adjacentregions of ECPC can provide connectivity along the Y axis (the “slowaxis”); while this is sub-optimal, judicious design can in some casesminimize the need for conductivity along this axis on a particularlayer, and the orientation of the raster can be varied from layer tolayer (e.g., by rotating the object) with interconnects designed (e.g.,automatically) to optimize resistance by selecting those layers offeringthe highest conductivity for the required interconnect directions. Withproper design (e.g., a vertically-quantized helix with polygonal sides)even coils can be produced with a raster-based approach. In raster-basedembodiments using an external capillary, two such capillaries may beprovided diametrically opposite the nozzle and in line with the rasterfast axis, so that filament delivery can occur bidirectionally. Inraster-based embodiments, ECPC-delivering nozzles may be positioned inline (e.g., two nozzles diametrically opposite the nozzle deliveringpure polymer, all aligned with the raster fast axis), such that ECPC canbe delivered through its own nozzle and switching between materials canbe avoided. In raster-based embodiments, multiple nozzles can be used,with some or all nozzles being capable of depositing filament, tosignificantly speed up layer formation. In some embodiment variations,one or more external capillaries can be mounted to a stage similar toFIG. 45(a) and move along the slow axis, providing wire embedding to oneor more particular nozzles for a given layer, then reposition near oneor more, possibly different, nozzles for a different layer.

In some embodiments, in lieu of or in addition to embedded solidconductors, small channels may be incorporated into the fabricatedobject which can be filled with conductive material in liquid or solidform. For example, small-diameter tubes may be integrated much likefibers into a structure, and filled (e.g., by capillarity) with a moltenlow melting-point metal alloy that is either maintained molten (e.g.,the device may operate in a heated environment, or the metal may bemelted through resistive heating using a current or by induction) orallowed to solidify. In some embodiments, conductive pathways may beformed by extruding a material having an interconnected porosityas-fabricated or upon further processing, and then infiltrating thematerial in selected regions with a conductive liquid, which in someembodiment variations can thereafter solidify. Interconnected pores maybe produced by injecting air bubbles during deposition in a mannersimilar to FIG. 71, by depositing a two-phase material (e.g., one havinga particulate in high concentration that is subsequently removed orevaporates to leave voids), or other methods.

In some embodiments it is desirable or necessary to provide a force thatbrings together or into closer proximity elements that are to be joined.For example, in the case of laser soldering, it may be advantageous toforce one wire against another or near another when making a wire-wirejunction, or force a wire against or near a component pad when making awire-pad junction. In the case of laser soldering of junctions, a tubemay be provided through which the laser beam propagates (e.g., between afiber collimator and its focal point). The tube can be designed suchthat its tip is of small diameter, but it does not intersect the beam,which may be converging: e.g., the tip may be tapered like a funnel. Inaddition to its possible uses as a safety shield for the laser beam anda means of withdrawing smoke and fumes produced during soldering byapplying vacuum to the tube, the tip of the tube (e.g., made from ametal) can be used to press together the objects to be joined, ensuringthey are in the proper position for joining. For example, in the case ofa ball grid array or similar device (packaged or bare) having an arrayof pads (versus pads only at the device edges), the device may be placedinverted within a printed structure and there are many wires which needto be soldered to the pads. These wires, especially if uninsulated, mayoriginate from various layers within the fabricated structure, and mustbe bent downwards by various amounts to make contact with the pads onthe device. Wires originating on lower layers may be used to connect topads near the periphery of the device, while wires originating on higherlayers may be used to connect to pads towards the interior of thedevice. Solder paste can be deposited onto the pads and then wire isprinted on a number of layers. Soldering can be performed gradually(e.g., as each layer of wires is added, additional pads are soldered) orall at once, the former being preferable such that wires originating onhigher layers do not shadow pads on lower layers, since the wires havenot yet been printed. While the wires from lower layer(s) may already bein contact or in proximity to their corresponding pads, wires on higherlayers will often need to be deformed so that they can reach down totheir corresponding pads. This deformation can be accomplished by use ofthe tube, which presses against the wire (in some embodiments a notchmay be provided in the tube to prevent the wire from slipping sideways),deforms it downward so that it touches or is near the pad, at whichpoint the laser can melt the solder paste (if the wire is sufficientlyductile or the paste sufficiently adhesive, the tube need not remain inplace during the soldering; otherwise, it can continue to hold the wirein position during the soldering operation).

An FDM-type 3-D printer may utilize multiple, independent extruders toproduce a part more quickly than is possible with a single extruder.However, such parts might normally be less strong than if made with asingle extruder due to weaknesses at the interface (e.g., vertical)between regions printed by different extruders. To greatly increase thesurface area of this interface and thus strength of the part, theworkspaces of two or more extruders can be made to overlap to someextent, and in the region of overlap, layers can be printed byalternating one extruder and another. This produces a part withpartially interleaved layers. To further increase strength, reinforcingfibers can be printed in the overlapping region in the form of“U”-shaped loops using FEAM-based printheads with extruders and WSFs.When matrix material is deposited by printhead A into loops formed byprinthead B (and vice-versa), the loops are embedded in matrix material,further binding the two regions of the part together.

It can be advantageous if the nozzle through which material is deliveredcan accommodate the presence of elements such as components to beembedded in the structure which protrude above the previous layer(rather than are flush or below flush with the layer upper surface, in acavity). While a standard FDM-type nozzle can achieve this to someextent, it requires leaving a wide, material-free margin around thecomponent, to avoid collisions. In some embodiments a nozzle maytherefore be used that is tilted in a vertical plane so that one side ofthe nozzle is no less than 90 degrees from the layer surface, allowingthe nozzle orifice to move much closer to the component and reducing themargin width or eliminating it entirely. Since such a nozzle is nolonger symmetric, it—or the structure being fabricated—must rotate ifthe nozzle path changes direction, so as to keep the side adjacent tothe component in the desired orientation.

In some embodiments devices can be produced with FEAM which have hiddenfunctionality and are thus useful in covert applications. Sensors aswell as antennae, processors, memory, power sources, and actuators canbe built-in or embedded. Such a device, for example, might appear like arock, but in fact serve as an unattended ground sensor for military orlaw enforcement use.

Soluble support materials such as PVA can be made to dissolve even morequickly if they are printed with sparse infill so they are much lessthan 100% dense. Moreover, support structures may be made withlattice-like structures or provided with channels to introduce thesolvent.

In some embodiments a FEAM or FDM machine can use interchangeabletoolheads, at least one of which can be mounted to a moving carriage andbe active at a time, while others await use in a storage area. Toolheadsmay include filament extruders (in which case the filament may remaininserted when the toolhead is in storage), pellet extruders (in whichcase a small hopper on the toolhead may be refilled while in storage),syringe extruders (e.g., for SMC, ECPC, solder paste), high-pressure ramextruders, spindles (for subtractive processing such as drilling andmilling), laser collimators (in which case an optical fiber may remainattached while the collimator is in storage), inspection microscopes,manipulators (e.g., vacuum, magnetic) for pick and place placement ofcomponents, etc. The carriage can move to a position where it can matewith a toolhead in a very repeatable fashion (e.g., using a kinematicmount, using a keyed taper). Mating electrical interfaces on thecarriage and toolhead can be provided so that electrical power andsignals can pass from carriage to toolhead and back. Commonly,frequently-used toolheads (e.g., build/model material and supportmaterial, or solder syringe extruder and collimator) may be loaded ontothe carriage simultaneously in some embodiments, to minimize the timeneeded for toolhead exchange. This approach also allows for off-linetoolhead maintenance (e.g., removing residue build-up on a nozzle,purging, priming, pre-heating) and provides redundancy (e.g., there canbe more than one printhead for a critical material).

In some embodiments, printed structures comprising a deformable wire andelastomer (or shape memory polymer) matrix may be reshaped afterfabrication. If the wire is plastically deformed by a force, theelastomeric structure can change shape permanently. If the wire iselastically deformed, the structure normally reverts to its originalshape after the force is removed. However, if the elastomer is heatedwhile the force is applied, then the elastomer may set into a new shape.After cooling, it remains in that shape without the application ofpower. Since there are residual stresses in the wires but the wires areunable to return to their original shape (in which the stresses arereleased), the structure is left with residual wire stresses. Ifreheated again, it will spontaneously change its shape based on thosestresses. Forces may be applied externally, or may be appliedinternally, e.g., electromagnetically, capacitively/using the principalof dielectric elastomer actuators, using shape memory effects, thermalexpansion, piezoelectric and magnetostrictive effects, etc.

In some embodiments, printed material can have features added to itafter printing. For example, printed thermoplastics can be embossedusing suitable tooling, e.g., to provide useful surface textures (e.g.,super-hydrophobic textures), channels to transfer fluids, etc.Alternatively, a printhead in which the nozzle or surrounding elementsis specially shaped (e.g., with small-scale protrusions) can emboss thepolymer as it prints.

In some embodiments FEAM may be implemented in a rectilinear fashionsuch that wires are only routed parallel to the X and Y axes (or othertwo axes, not necessarily separated by 90 degrees), and in someembodiment variations, while moving the printhead only in a positive Xor positive Y direction (or the inverse). When so implemented, twoseparate WSFs can be used: one for depositing wires parallel to X, andone for depositing wires parallel to Y, and no WSF rotation is needed,thus potentially reducing cost and complexity. Junctions are formedbetween X and Y wire segments as needed to obtain the desired circuitrouting.

In the FEAM process, it is useful in some embodiments to vary the feedrate of wire according to the radius of the path followed by the nozzlewhile printing wire and matrix. If the wire is fed faster, it will moveto the outside of a curve; if the wire not fed more slowly, it will moveto the inside of the curve.

Slightly underfeeding wire (feeding at a lower speed than the printheadtangential velocity) or other methods can be used to provide a slighttension in the wire to prevent it from wandering within the capillary,which can affect its location in the extrudate.

3-D printing may be performed in a granular gel medium into which amaterial is delivered through a needle or similar, with the granular gelsupporting the delivered material [O'Brian et al., 2017]. In someembodiments, FEAM can also be performed in a granular gel medium, suchthat in addition to the delivered material, a fiber is delivered intothe gel. The fiber may be encapsulated by the delivered material, or insome embodiment variations be adjacent to it.

Continued, uncontrolled leakage of material from a nozzle isundesirable. While a filament extruder can reverse the direction offilament motion to reduce pressure in the nozzle to minimize this, itcan be more difficult with a screw-based extruder. In some embodimentspressure reduction can be implemented by incorporating a crushable tube(e.g., thick-walled silicone, superelastic Ni—Ti) into the printhead.Under normal extrusion conditions, the tube is kept partially crushed(e.g., by an actuator). When a reduction in pressure is needed, pressureis released (at least partially) allowing the tube to increase in size.Such an arrangement allows for an easily-cleaned device.

In some embodiments in lieu of a downstream capillary adjacent to thenozzle, pins are provided which protrude from the nozzle, or a groove isprovided in the nozzle, to control the wire position.

In some embodiments, the printhead is equipped with a “hot shoe” whichsmooths and reflows the surface of the extrudate so as to reduceporosity (by reflowing/pushing together neighboring extrudates). Theshoe can also increase intra-layer bonding and improve thickness controland surface finish of up-facing surfaces.

The accuracy and repeatability of an FDM or FEAM printer is to someextend a function of the width of the extrudate, and this is a functionin part of extrudate diameter, which can vary over some range. In someembodiments between the “cold end” of the printhead (e.g., driven andidler rollers) one can incorporate a sensor that measures the localdiameter of the filament, allowing the roller speed to be adjusted inreal time such that extrusion flow rate is constant, regardless of smalldiameter variations.

Calibration (preferably automatic and periodic) of the fiber feed speedcan be performed in some embodiments for different wire types,hardnesses, diameters, shapes, and to compensate for wear of the rollers(or other mechanism) that feeds the wires.

In some embodiments, ECPCs may be conditioned for use by a “burn-in”process which subjects the ECPC to an electrical current, an elevatedtemperature, etc., with the result that the resistivity of the ECPC isstabilized and may be decreased.

When flat wire, or wire that is locally flattened is used forintra-layer junctions, in some embodiments it is preferentially orientedso that the wider dimension is vertical, allowing solder paste to bedispensed into or near the gap between the wires.

A system containing multiple electromagnetic devices with permanentmagnetic materials that are deposited is most easily magnetized if thedesired field orientations of all the magnets are arranged to beparallel.

In some embodiments, laser-induced forward transfer (LIFT) may be usedto deposit solder, solder paste, ECPC, magnetic materials, etc. inconjunction with an FDM or FEAM process.

In some embodiments small errors in fiber feed rate may cause undesiredbuildup of tension. This can be corrected in some embodiments by havingthe fiber execute a turn while unembedded in material, enter a cavity,etc. to provide slack.

FEAM and Big Area Additive Manufacturing (BAAM, a scaled-up form of FDMtypically using pellet-fed extruders) may be combined, allowinglarge-scale structures such as car, boat, and aircraft bodies, as wellas major appliances, to be built with built-in wiring and/or continuousfiber reinforcement.

Artificial pressure/touch-sensing “skin” (e.g., for robots) can beproduced in which a powdered conductive material (e.g., carbon black) isdispersed in an elastomeric matrix, and electrodes (e.g., formed fromwire) are connected with wire to measure the resistivity change ofregions of the structure when they are subject to forces (compressive,tensile, shear, etc.), which can alter the resistance by altering theaverage distance between particles.

FEAM can be used to check for faults in manufactured parts (e.g., tocounter cyber-attacks or to indicate when parts have failed or are aboutto fail (from otherwise normal usage). For example, strain gauges orpiezoresistive elements can be incorporated throughout the part (perhapsmanufactured using ECPC) and connected with wires to a central sensingunit. If ECPC is used as the sensing element, carbon black can be used,for example, at low concentrations to obtain good material propertiesbut high resistance, as could conductive inks.

To enhance the thermal management of heat-sensitive components within3DPHEMs, etc., thermally-conductive paste and adhesives may be dispensedadjacent to the component.

Control System

The control of the apparatus and the implementation of the methods andsteps described herein may be achieved using hardware, software, or anycombination thereof, together forming a control system. The term“hardware” may refer to either one or more general or special purposecomputers; microcontrollers; microprocessors; embedded controllers; orother types of processor, any of which may be provided with a memorycapability such as static or dynamic RAM (random access memory);non-volatile memory such as ROM (read only memory); EPROM (erasableprogrammable read only memory), or flash memory; magnetic memory such asa hard drive; optical storage media such as CD (compact disc) or DVD(digital versatile disc); etc. The term may also refer to a PAL(programmable array logic) device, an ASIC (application specificintegrated circuit), an FPGA (field programmable gate array), or to anydevice capable of processing and manipulating electronic signals.

The term “software” may refer to a program held in memory, loaded from amass storage device, firmware, and so forth. The program may be createdusing a programming language such as C, C#, C++, Java, or any otherprogramming language, including structured, procedural, and objectoriented programming languages; assembly language; hardware descriptionlanguage; and machine language, some of which may be compiled orinterpreted and use in conjunction with said hardware.

The control system may serve to load files, perform calculations, outputfiles, control actuators such as motors, voice coils, solenoids, fans,and heaters, and acquire data from sensors, to automate or semi-automateapparatus which can implement the methods and steps described herein.Each method described herein, including any sequential steps that may betaken for the method's implementation and any modification of thebehavior of the apparatus or control system as a result of human orsensor input, as well as combinations of such methods, may beimplemented and performed by the control system, executing a program, orcode, embodied in the control system. In some embodiments, multiplecontrol systems may be employed, and portions of the functionality ofthe control system may be distributed across multiple pieces of hardwareand/or software, or combined into a single piece of hardware running asingle piece of software.

General

The terms “wire” and “fiber” are generally speaking and for the mostpart used interchangeably herein, referring to elements that can beco-deposited, laid, encapsulated, and/or embedded within anothermaterial to form a composite structure or material. Moreover, the term“filament”, unless it is referring to the form of the material fed intoa printhead, may be taken to be synonymous with the terms “wire” and“fiber” as described in this paragraph. The term “wire” does notnecessarily imply metal, nor does “filament” or “fiber” necessarilyimply a material other than metal.

It is contemplated that any embodiment discussed in this specificationcan be implemented with respect to any method, kit, reagent, orcomposition of the disclosure, and vice versa. Furthermore, compositionsof the disclosure can be used to achieve methods of the disclosure.

It will be understood that particular embodiments described herein areshown by way of illustration and not as limitations of the disclosure.The principal features of this disclosure can be employed in variousembodiments without departing from the scope of the disclosure. Thoseskilled in the art will recognize, or be able to ascertain using no morethan routine experimentation, numerous equivalents to the specificprocedures described herein. Such equivalents are considered to bewithin the scope of this disclosure and are covered by the claims.

All publications and patent applications mentioned in the specificationare indicative of the level of skill of those skilled in the art towhich this disclosure pertains. All publications and patent applicationsare herein incorporated by reference to the same extent as if eachindividual publication or patent application was specifically andindividually indicated to be incorporated by reference.

The use of the word “a” or “an” when used in conjunction with the term“comprising” in the claims and/or the specification may mean “one,” butit is also consistent with the meaning of “one or more,” “at least one,”and “one or more than one.” The use of the term “or” in the claims isused to mean “and/or” unless explicitly indicated to refer toalternatives only or the alternatives are mutually exclusive, althoughthe disclosure supports a definition that refers to only alternativesand “and/or.” Throughout this application, the term “about” is used toindicate that a value includes the inherent variation of error for thedevice, the method being employed to determine the value, or thevariation that exists among the study subjects.

As used in this specification and claim(s), the words “comprising” (andany form of comprising, such as “comprise” and “comprises”), “having”(and any form of having, such as “have” and “has”), “including” (and anyform of including, such as “includes” and “include”) or “containing”(and any form of containing, such as “contains” and “contain”) areinclusive or open-ended and do not exclude additional, unrecitedelements or method steps.

The term “or combinations thereof” as used herein refers to allpermutations and combinations of the listed items preceding the term.For example, “A, B, C, or combinations thereof” is intended to includeat least one of: A, B, C, AB, AC, BC, or ABC, and if order is importantin a particular context, also BA, CA, CB, CBA, BCA, ACB, BAC, or CAB.Continuing with this example, expressly included are combinations thatcontain repeats of one or more item or term, such as BB, AAA, AB, BBC,AAABCCCC, CBBAAA, CABABB, and so forth. The skilled artisan willunderstand that typically there is no limit on the number of items orterms in any combination, unless otherwise apparent from the context. Incertain embodiments, the present disclosure may also include methods andcompositions in which the transition phrase “consisting essentially of”or “consisting of” may also be used.

As used herein, words of approximation such as, without limitation,“about”, “substantial” or “substantially” refers to a condition thatwhen so modified is understood to not necessarily be absolute or perfectbut would be considered close enough to those of ordinary skill in theart to warrant designating the condition as being present. The extent towhich the description may vary will depend on how great a change can beinstituted and still have one of ordinary skilled in the art recognizethe modified feature as still having the required characteristics andcapabilities of the unmodified feature. In general, but subject to thepreceding discussion, a numerical value herein that is modified by aword of approximation such as “about” may vary from the stated value byat least ±1, 2, 3, 4, 5, 6, 7, 10, 12 or 15%.

All of the compositions and/or methods disclosed and claimed herein canbe made and executed without undue experimentation in light of thepresent disclosure. While the compositions and methods of thisdisclosure have been described in terms of preferred embodiments, itwill be apparent to those of skill in the art that variations may beapplied to the compositions and/or methods and in the steps or in thesequence of steps of the method described herein without departing fromthe concept, spirit and scope of the disclosure. All such similarsubstitutes and modifications apparent to those skilled in the art aredeemed to be within the spirit, scope and concept of the disclosure asdefined by the appended claims.

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The invention claimed is:
 1. A method for segmenting and feeding a fibercomprising: providing a continuous fiber; providing a capillary having alumen; advancing the fiber through the lumen in a downstream direction;locally damaging the fiber in a region upstream of the capillary;advancing the fiber downstream until the damaged region is inside thecapillary; clamping the fiber inside the capillary at a locationdownstream of the damaged region so the fiber cannot move; applyingtension to the fiber upstream of the capillary to break the fiber in thedamaged region and yield a downstream wire segment; releasing thedownstream wire segment within the capillary so the downstream wiresegment can be advanced; advancing the downstream wire segment bypushing the downstream wire segment with the fiber upstream of thesegment, wherein a fiber segment of the desired length is delivered bythe capillary.
 2. The method of claim 1, wherein the advancing isachieved by rotating at least one roller in contact with the fiber. 3.The method of claim 1, wherein the damaging is achieved by advancing ablade into the fiber.
 4. The method of claim 1, wherein the clamping isachieved by compressing the capillary.